Phuc Chat (Full)

8/14/2019 Phuc Chat (Full)

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TRNG AI HOC A LAT

GIAO TRNH

HOA HC PHC CHAT

PHAN BA NGAN2002


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Giao trnh hoa hoc phc chat 2

Chng I. M AU

I. KHAI NIEM PHC CHAT

T cac kien thc a hoc, chung ta gap 2 loai hp chat:- Hp chat n gian hay cac hp chat bac nhat c tao thanh t cac ion,

nguyen t hoac cac goc ket hp vi nhau. V du: CuO, NaOH, HCl,- Hp chat phc tap hay cac hp chat bac cao (hp chat phan t): AgCl.2NH 3,

CoCl3.6NH3,Chung c tao thanh t cac phan t hp chat n gian.

nh ngha:

Vecne: Phc chat la nhng hp chat phan t (bac cao), ben trong dung dchnc, khong phan huy hoac phan huy rat t ra cac hp phan tao thanh chung. V

du:

CoCl3.6NH3 = Co(NH3)63+ + 3 Cl- , hoan toan

Co(NH3)63+ Co 3+ + 6NH3 , khong hoan toan

Grinbe: Phc chat la nhng hp chat phan t xac nh, khi ket hp cac hpphan cua chung lai th tao thanh cac ion phc tap tch ien dng hay am, co khanang ton tai dang tinh the cung nh trong dung dch. Trong trng hp riengien tch cua ion phc tap o co the bang khong.V du: Cu(NO3)2. 4Py.

Iaximirxki: Phc chat la nhng hp chat tao c cac nhom rieng biet t

cac ion, nguyen t hoac phan t vi nhng ac trng:- Co mat s phoi tr.- Khong phan ly hoan toan trong dung dch.- Co thanh phan phc tap (so phoi tr va hoa tr khong trung nhau).

II. PHAN LOAI PHC CHAT

1.Phan loai theo tnh chat gan nhau:

Ngi ta phan ra cac loai nh : cac hydrat, cac amiacat, ancolat,

2.Phan loai theo ien tch:- Cation phc: Ion phc tap tch ien dng, V du: [Co(NH3)6]3+- Anion phc: Ion phc tap tch ien am, V du: [PtCl6]2-- Phc chat trung tnh: Phan t phc chat trung hoa ien, V du: [Cu(NO3)2].4Py]

III. S LC VE VAI TRO, Y NGHA CUA HOA HOC PHC CHAT:

Trong hoa hoc phan tch: Hau het cac phan ng phan tch nh tnh va nhlng eu da vao s tao phc cua cac cau t.

V du: Co the dung phng phap trac quang e xac nh cac ion kim loai:

Phc chat [TiO(H2O2)2]2+ co mau vang e xac nh Ti4+

Phan Ba Ngan Khoa hoa hoc


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Phc chat [CuPy2(SCN)2] mau xanh e xac nh Cu2+

Phc chat nikendimetylglyoxim mau o e xac nh Ni2+

Trong ky thuat: dung s tao phc e tinh che, tach cac kim loai ac biet la cackim loai quy:

V du: Trong hon hp Pt, Pd, Ru, Fe, Co, Ni, Cu, ngi ta co the dung NaNO 2trong moi trng kiem th cac kim loai Fe, Co, Ni, Cu se ket tua di danghydroxyt, con Pt, Pd va Ru th tao phc ben tan trong nc dang Na2[Me

IV(NO2)6],Na3[MeI(NO2)4].

e tach uran ngi ta dung Na2CO3 th cac kim loai khac ket tua di danghydroxyt hoac cacbonat, con uran tao phc tan vi CO32- dang Na4[UO2(CO3)3].

Co the tach rieng cac kim loai hiem va at hiem co nhieu tnh chat ly, hoa hocgiong nhau nh cap Nb-Ta, Zr-Hf, Pr-Nd bang cach da vao s tao phc khac nhau

cua chung vi cac phoi t hu c va tach chung bang phng phap chiet, trao oiion,

Trong lnh vc cong nghiep, phc chat thng c dunglam mem nc, thuocnhuom, thuoc da, nhiep anh, ma kim loai,

Trong sinh hoa, chang han hemoglobin (co trong thanh phan cua mau ngi vaong vat) gom co chat anbumin goi la "globin" va mot hp chat mau "hemo".Hemo la mot phc chat ma nguyen t trung tam la sat va cac phoi t la cac nhompyrol. Clorofil la chat mau xanh cua thc vat co cau tao giong nh cua hemoglobinnhng nguyen t trung tam la magie. Insulin la dan xuat phc cua kem con

vitamin B12 la dan xuat phc cua coban,Ngoai ra phc chat con ong vai tro toc o ln trong lnh vc hoa hoc ly thuyet.

Lc s phat trien cua hoa hoc phc chat :

1893-1940 la thi ky tong hp cac phc chat khac nhau cua Co3+, Cr3+ va cackim loai quy nh Pt2+, Pt4+,

1941-1960 la thi ky nghien cu thanh phan, cau tao cua phc chat bang cacphng phap hoa ly.

1961 en nay la thi ky dung cac phng phap vat ly hien ai e nghien cuphc chat.



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Chng II. THUYET CAU TAO PHC CHAT

Tnh chat cua phc chat c quyet nh bi hai yeu to sau ay:

1- S sap xep khong gian cua cac nhom xung quanh ion kim loai hay noi cachkhac la cau tao cua phc chat.

2- Ban chat cua lien ketgia cac nhom vi ion kim loai (o ben cua lien ket,mc o ion hoac cong hoa tr cua lien ket).

Ly thuyet ve cau tao cua phc chat phai giai thch c cac van e sauay:

+ Cac quy luat xac nh thanh phan cua phc chat.

+ Hien tng ong phan cua phc chat.

+ Tnh chat khac nhau cua lien ket gia cac phan t, ion vi kim loai.Co hai kieu lien ket :- Lien ket theo kieu ion: cac ion linh ong, de tham gia phan ng trao oi.- Lien ket kieu khong ion: cac goc hay cac ion khong linh ong, hau nh

khong tham gia phan ng trao oi.

V du: Trong hp chat CoCl3.5NH3 th ch co 2 ion Cl- lien ket vi Co3+ theokieu ion nen de cho phan ng ket tua AgCl, con mot ion Cl- lien ket khong ion viCo3+, khong cho phan ng ket tua AgCl.

I. CAC THUYET CU1. Thuyet amoni (Graham):

Graham cho rang co the coi cac amoniacat kim loai nh la cac hp chat amonib the, trong o amoniac ket hp vi muoi kim loai. Phan ng :

CuCl2 + 2NH3 = CuCl2.2NH3

Giong nh phan ng :

HCl + NH3 = NH4Cl

Co the coi ion Cu2+ thay the hai ion H+ cua hai phan t NH4Cl va cau tao cuahp chat CuCl2.2NH3 co the viet:

ClNH3-Cu-NH3Cl

Theo cong thc tren, Cu hoa tr hai thay the hai ion H+ (cua hai nhom NH3). Caccong thc tng t cong thc tren ch ung khi hoa tr cua kim loai bang so nhomNH3 trong hp chat. That vay, trong hp chat CoCl3.6NH3 khong the bieu dienc cau tao theo kieu muoi amoni b the c v Co ch co hoa tr ba nhng lai cosau nhom NH3. Sau nay Hoffman va Reisset co cai tien thuyet amoni nhng noichung cung khong the dung thuyet amoni e giai thch cau tao cua cac amoniacat

c.



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Mat khac, chang han muoi CoCl3.6NH3 con co the viet c mot cong thc cautao khac nh sau:

NH3 - NH3 - Cl

CoCl3.6NH3 : Co - NH3 - NH3 - Cl

NH3 - NH3 - Cl

Nh vay, hp chat tren ve mat ly thuyet co the ton tai t nhat hai dang ongphan nhng tren thc te ch co mot hp chat tng ng cong thc o. Ngoai ra, khiviet cong thc cau tao cho cac hp chat o dai mach tuy tien c viet theo y chuquan nhng thc te khong co nhng dang ong phan a viet. o la nhng iemyeu cua thuyet mach.

II. THUYET PHOI TR (VECNE 1893)- a so cac nguyen to the hien 2 kieu hoa tr: chnh (so oxyhoa) va phu (so

phoi tr)- Moi nguyen to eu muon bao hoa ca 2 loai hoa tr o- Hoa tr phu hng en nhng v tr co nh trong khong gian.T cac luan iem tren, Vecne a ra khai niem cau tao tam : ion trung tam, cacion, phan t khac la cac phoi t . Ve ban chat khong phan biet hoa tr chnh, phu.

1. S phoi tr:

La hien tng cac phoi t phan bo xung quanh ion trung tam vi mot s oixng nhat nh

2. So phoi tr (spt) cua ion trung tam:

La so phoi t lien ket trc tiep:- Cac ion trung tam co mc oxyhoa nhat nh co so phoi tr tng ng: Pt2+ :

4; Pt4+ : 6- Mot so trng hp ion trung tam co so phoi tr khong oi, khong phu thuoc

ban chat phoi t va ieu kien ben ngoai.

V du: Co3+, Cr3+, Fe2+, Fe3+, Pt4+, Ir3+,Ir4+ eu co spt 6

Pt2+,Pd2+ spt 4

- a so trng hp, so phoi tr cua ion trung tam thay oi phu thuoc ban chatphoi t va ieu kien ben ngoai.

V du: Cu2+ co spt la 3,4,6 ; Ni 2+, Zn2+ spt 3,4,6

3.Dung lng phoi tr (dlpt) cua phoi t:

La so v tr ma phoi t chiem c ben canh ion trung tam.

Phoi t co 1 lien ket - dlpt 1. V du: cac goc axit hoa tr 1, cac phan t NH3,C5H5N, C2H5NH2, H2O, C2H5OH,.

Phoi t co 2 lien ket - dlpt 2. V du: Etylendiammin, SO42-



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4.Danh phap phc chat: theo IUPAC 1960:au tien goi ten cation, sau o ten anion.- Ten goi cac nhom tch ien am tan cung bang ch o, cac phan t trung hoa

c goi theo ten, tr H2O- aqu , NH3- ammin.

- So lng cac phoi t cung kieu c ch bang ch so HyLap: di, tri,tetra,.Neu co cac phoi t hu c phc tap th them cac tiep au ng nhbis,tris,tetrakis,e ch so lng cua chung.

- Hoa tr cua ion trung tam c ch bang ch so La Ma e trong ngoac nsau ten kim loai- neu goi ten cation phc hay phc khong ien ly, hoac sauuoi at- neu la anion phc.

- Cac phoi t c goi trc het la anion , phan t trung hoa va sau o lacation, cac phoi t cung kieu (ion +,- hoac phan t trung hoa) c goi theoth t ABC.

- Neu 1 nhom lien ket vi 2 nguyen t kim loai th goi ten no sau cac nhomkhac, trc ten goi cua no at ch Hy Lap .

- Cac ong phan hnh hoc c ky hieu bang ch au cis hoac trans tngng.

V du: [CoEn2Cl2] Cl dicloro bis- etylendiammin coban (III) clorua.

NH4[Cr(NH3)2(NCS)4] - amoni tetratioxianato diammin cromat (III).

5.ong phan cua phc chat:

- ong phan hnh hoc+ Phc chat co so phoi tr 4: Vao thi ky cua Vecne, mac du cha co

nhng phng phap hien ai e nghien cu cau truc phc chat nhng vilap luan cua mnh ket hp vi nhng d kien thc nghiem Vecne achng minh c phc chat cua Pt2+, Pd2+ vi so phoi tr 4 co cau hnhvuong phang.

+ Phc chat co so phoi tr 6: Bang cach tng t, Vecne chng minh phcchat vi so phoi tr 6 co cau hnh bat dien

- ong phan quang hoc: Tng t nh cac hp chat hu c, phc chat cung cothe co ong phan quang hoc do s bat oi xng cua toan bo phan t hoac dos bat oi xng cua phoi t hu c.



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Chng III. BAN CHAT LIEN KET TRONG PHC CHAT

I. CAC THUYET CU

1. Thuyet tnh ien COXEN (KOSSEL)

Theo Coxen, phc chat tao thanh do lc hut tnh ien gia cac ion tch ien traidau hoac gia ion va phan t lng cc (lien ket ion - ion va lien ket ion - lngcc).

Moi ion tao nen mot ien trng co ng sc nam trong vung gia cac ion, vthe ma ion co the ket hp them cac ion hoac cac phan t lng cc.

Tnh nang lng tao thanh cua phc chat: Coxen va Magnus:

Gia thiet cac ion la nhng qua cau cng, co ban knh nh nhau va tng tac vinhau theo nh luat Culong (Coulomb).

V du: Ion phc tao thanh [Ag(CN)2]-

CN- Ag+ CN-

___r___- Theo nh luat Culong: Fhut = e2/r2 . Fay = e2/4r2- Theo Coxen va Magnus th o ben cua phc chat tao thanh phu thuoc vao

ty le gia lc hut va lc ay:

Hang so chan S = F/Fh = 0,25

Bang 1: Hang so chan S oi vi ion kim loai hoa tr 1 ket hp vi 1,2,3,4 ion amhoa tr 1 vi cau hnh khong gian tng ng.

So pt n Cau hnh khong gian cua p/c Hang so chan S

2 ng thang 0,25

3 Tam giac eu 0,58

4 T dien eu 0,92

4 Hnh vuong 0,96

Nang lng tao thanh phc chat: Xet trng hp tong quat, khi ion trung tamco hoa tr khac nhau con cac ion am co hoa tr 1. Nang lng tao thanh phc chatU (nang lng thoat ra khi tao thanh phc t cac ion rieng re) la:

U = n (Z-S) e2/r

n- so phoi tr, Z- ien tch ion trung tam, S- hang so chan



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U khong nhng phu thuoc vao so phoi tr n ma con phu thuoc vao s sap xepkhong gian cua cac phoi t .

Khi r = const th ai lng M = n (Z-S) se ty le vi nang lng tao thanh U, taco bang sau:

Z\n 1 2 3 4 5 6 7 8

1 1,00 1,50 1,26 0,32

2 3,50 4,26 4,32 3,12 2,04

3 7,26 8,32 8,12 8,04 4,90

4 12,32 13,12 14,04 11,90 12,24

Nhan xet: Thc te ton tai cac phc chat [CuCl3]- , [CuCl4]2- va [AuCl4] -, .

Tren thc te, so phoi tr cua ion trung tam con phu thuoc vao ban knh cua nova cua cac phoi t, V du: [BF4]- va [AlF6]3- hay [AlF6]3- va [AlCl4]-

S d co sai lech tren la do khi tnh toan a gia thiet cac ion co ban knh r nhnhau. Sau nay khi co cac d kien ve ban knh r cua cac ion th bo sung vao viectnh toan. Tat ca cac tnh toan ve U ch ung khi cac ion tiep xuc vi nhau. ieuo ch co the thc hien c khi ty so rM/rX at c mot gia tr nao o. Lembegoi o la ty so ti han.

Moi lien he gia so phoi tr n, ty so ti han va cau hnh khong gian cua ionphc c Lembe a ra bang sau (coi rM = 1).

N rX/rM rM/rX Cau hnh khong gian2 - - ng thang

3 6,464 0,15 Tam giac eu

4 4,449 0,22 T dien

6 2.414 0,41 Bat dien

8 1,366 0,73 Hnh khoi

Da vao bang nay giai thch mot so d kien thc nghiem. V du:

Noi chung ion hoa tr 4 co so phoi tr la 6. Tuy nhien co mot so ngoai le: Si4+tao phc SiF6

2- ma khong nhan c cac phc tng t oi vi Cl-, Br- , I-. oi viSn4+ th ngoai cac phc dang [SnX6]2- con biet [SnF8]4-. Co the giai thch ieu naynh sau:

oi vi Sn: rSn4+/rF

- = 0,56 , rSn4+/rBr

- = 0,38

rSn4+/rCl

- = 0,41 , rSn4+/rI

- = 0,34

Mot cach tng t, co the giai thch c so phoi tr cua N hoa tr 5 la 3 trongNO

3

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Ngoai nhng thanh cong tren, thuyet tnh ien con co mot so nhc iem nh:khong giai thch c mau sac cua phc chat, khong giai thch c toc o chamcua mot so phan ng, hay tai sao mot so phc chat kim loai hoa tr 2 nh Pt, Pd laico cau hnh vuong phang ma khong co cau hnh t dien thuan li hn.

2. S phan cc Ion va Phan t:e giai thch mot so van e ton tai trong thuyet tnh ien Faijan a ra khai

niem phan cc: Di tac dung cua ion trung tam a hoa tr, lp vo electron cuaphoi t se dch chuyen ve pha ion trung tam lam xuat hien mot lng cc camng trong phoi t. Ket qua lam tang o lien ket gia ion trung tam va phoi t. Quatrnh nay xay ra cang manh khi ai lc electron cua ion trung tam cang ln :

_

L M L

Giai thch mot so trng hp:

Cac ion kim loai kiem va kim loai kiem tho khong tao c amoniacat bentrong dung dch nc nhng lai tao c hydrat kha ben, ngha la lien ket M-NH3yeu hn lien ket M-OH2. S d nh vay la do momen lng cc vnh cu cua nc(1,84 D) cao hn cua amoniac (1,44 D). Trong khi o, amoniacat cua cac ion Cu,Ag, Cd, Zn, lai ben trong dung dch nc hn la hydrat cua chung.

Giai thch: Lc hut gia ion va phan t phu thuoc vao cng o ien trng tao

bi ion trung tam va vao momen lng cc tong cong cua phoi t la momen lngcc vnh cu va momen lng cc cam ng:

t/c = v/c + c/

Amoniac co v/c thap hn cua nc nhng lai co o phan cc ln hn. V vaydi tac dung cua cac cation phan cc manh (cac kim loai chuyen tiep Cu,Cd,)t/c cua amoniac se cao hn cua nc.

Bang 2:Nang lng tao thanh cua hp nhat (theo Van Arken):

Phc chat Khong tnh en s p/c Co tnh en s p/c

cua phoi t cua phoi t[Ag(H2O)2]+ 41 cal 44 cal

[Ag(NH3)2]+ 40 cal 49 cal

Giai thch c che tao phc kieu polyhalogenua : [KI3], [KICl2] .

Trong dung dch nc:

[KI3] = K+ + I3-

Coi I3- la san pham ket hp cua I2 va I-



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Trong day F2 , Cl2 , Br2 va I2 va F-, Cl-, Br- , I- o phan cc tang len nen cacpolyiodua ben nhat con cac polyflorua kem ben nhat (cha tach c).

Ta cung co o ben tang theo day:

F3- Cl3- Br3- I3-

F-X2 Cl-X2 Br-X2 I-X2

X-F2 X-Cl2 X-Br2 X-I2

3. Thuyet lien ket cong hoa tr LIUYT (LEWIS)

Theo Liuyt th lien ket cong hoa tr c thc hien bang mot cap electron theohai cach: gop chung (lien ket cong hoa tr thuan tuy) hoac cho-nhan (lien ket phoitr). Trong ca 2 trng hp lp vo electron ben ngoai cua ca 2 nguyen t eu atc cau hnh ben cua nguyen t kh tr tng ng - la ong lc cua s tao thanh

hp chat hay phc chat noi rieng.

Liuyt ap dung e giai thch s tao thanh phc chat va sau o c Xituych phattrien.- Hoa tr chnh c o bang so electron ma nguyen t bo ra e tao thanh cac

cap electron lien ket- Hoa tr phu la hoa tr phat sinh do viec ien cac cap electron cua phoi t vao

cac o trong co nang lng thch hp cua nguyen t (ion) trung tam.

So th t nguyen t hieu dung (SND): la so electron tong cong cua ion (nguyent) trung tam va cua phoi t gop vao va a so bang so th t cua nguyen t kh trtng ng.

Cach tnh SND: = So e cua phoi t cho + hoac - so e ng vi ien tch cua ionphc (cong neu ien tch ion phc la am va ngc lai) cong vi so th t Z cuanguyen t trung tam.

Gia thiet, moi H, goc axit cho 1 e, con moi phan t trung hoa cho 2 e.

V du:

[Co(NH3)6] Cl3 : SND = 6x2 - 3 + 27 = 36 (Kr)

[Co(NH3)4Cl2]Cl: SND = 4x2 + 2x1 - 1 + 27 = 36

[K2 PtCl6] SND = 6x1 + 2 + 78 = 86 ( Rn)

[Pt(NH3)6]Cl4 SND = 6x2 - 4 + 78 = 86

T SND co the xac nh c so phoi tr cua kim loai ( SND = Z kh tr )

Trng hp ngoai le : [Ag(NH3)2]+ , SND cua Ag bang 50 (Xe 54).

Cac cacbonyl va nitrozyl kim loai va cac dan xuat cua chung thng tuan theoung quy tac ve SND, vi gia thiet 1 phoi t CO cho 2e, 1 phoi t NO cho 3 e (vNO+ cung so e vi CO).

Neu SND = Z th hp chat la monome

SND = Z+1 th hp chat la dime

SND = Z+2 th hp chat la trime



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Hp chat Z So e cua phoi t SND Sai lech Trang thai l ien hp phan t

Ni(CO)4 28 8 36 0 monome

Fe(CO)4I2 26 10 36 0 -

HCo(CO)4 27 9 36 0 -Co(CO)4 27 8 35 1 dime [Co(CO)4]2

HNi(CO)3 28 7 35 1 - [HNi(CO)3]2

Fe(CO)4 26 8 34 2 trime [Fe(CO)4]3

SND cua moi nguyen t Co trong dime (CO)4Co-Co(CO)4 van bang 36:

So e cua moi Co 27

So e cua 4 CO 8

So e cua moi Co trong l/k Co-Co 1------

36

T nhng ieu tren chung ta thay rang ve hnh thc thuyet nay cung giai thchc s tao thanh cua nhieu phc chat nhng no khong giai thch c cac tnhchat ly, hoa hoc cua phc chat.

II. CAC THUYET LNG T

1. Thuyet lien ket hoa tr (LH hay VB- valence bond)

ay la thuyet lng t au tien giai thch ban chat lien ket trong phc chat.

C s:

Lien ket hoa hoc trong phc chat gom nhng lien ket 2 electron kieu Hetle-Lndn (2 electron co spin oi song) gia nguyen t trung tam va cac phoi t. Solien ket nh vay phai bang so phoi tr cua ion trung tam.

So electron lien ket c chuyen t cac phoi t cho ion trung tam theo kieucho-nhan. Nh vay tai ion trung tam phai ton tai nhng trang thai thch hp cho

cac electron. Tai ion trung tam, cac AO co nang lng va hnh dang khac nhau laihoa vi nhau tao thanh nhng AO lai hoa co nang lng va hnh dang giong nhau.

ieu kien lai hoa: cac AO gan nhau ve nang lng, co oi xng giong nhau.

C N AO tham gia lai hoa se tao thanh N AO lai hoa.

Ve mat toan hoc: Cac AO lai hoa la s to hp tuyen tnh cac AO vi nhng heso thch hp.

V du :

Xet s tao phc [Ti(H2O)

6]3+ , Ti 3+ co cau hnh 3d1



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Khi tng tac vi Cl-, cac cap electron cua Cl- phan bo vao cac AO tiep theocua Ni (do ion Cl- co ban knh ln nen tng tac yeu vi Ni2+). Ta co [NiCl4]2- :

3d 4s 4p

Phc t dien, lai hoa sp3 , S= 1, thuan t

Trong khi o Ni2+ tng tac vi CN- rat manh nen s tao phc xay ra s ghepoi electron. Ta co [Ni(CN)4]2- :

3d 4s 4p

Phc vuong phang, lai hoa dsp2, S=0, nghch t

Nh vay, da vao spin toan phan cua he, co the suy oan tnh chat t cua phcchat. Ngc lai, khi o momen t toan phan cua he bang thc nghiem co the xacnh c so electron oc than trong o va t o suy ra cau hnh cua phc chat.

oi vi ion kim loai chuyen tiep, cac electron oc than nam AO (n-1) d thmoment lien he vi so e oc than n bang he thc gan ung sau ay:

n(n+2)

Khi o momen t cua phc chat [FeF6]3- va [Ni(NH3)6]3+ thay rang cac phcchat ng vi 5 electron va 2 electron oc than tng ng. Trong cac phc chat okhong the co lai hoa d2sp3 (lai hoa trong). ieu nay ch co the giai thch bang slai hoa kieu sp3d2 (lai hoa ngoai).

Vay cau tao cua phc chat tren co the mo ta n gian la :

[FeF6]3-

3d 4s 4p 4d

[Ni(NH3)6]3+

3d 4s 4p 4d

Xet o ben phc chat theo thuyet LKHT:

o ben cua phc chat c xac nh bang ai lng che phu cac AO. ailng che phu cang ln th o ben phc chat cang ln. ai lng che phu c xac



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nh bang tch phan che phu AB d (A, B la ham song cua cac nguyen tA, B; d la yeu to the tch).

V phan ban knh cua ham song hau nh khong xac nh c ma ch co thexac nh phan goc cua no nen khong the xac nh c ai lng che phu thc.

Bi vay khi muon so sanh nh tnh o ben cua lien ket ngi tacoi gia tr cc aicua phan goc nh la o o quy c vung che phu cc ai . V cac AO lai hoa cophan goc nh hng rat ro ret theo mot hng xac nh nen cac lien ket taothanh bi chung co o ben ln hn ca. ieu nay c xac nhan bang thc nghiemve o ben cua cac phc chat.

o ben cua lien ket trong phc chat gia kim loai va phoi t con phu thuocvao kha nang tao thanh lien ket kep. Khi co s tao thanh lien ket kep, o ben cualien ket se tang len.

cac phc chat bat dien, cac electron cua nguyen t trung tam phan bo mot

phan hay hoan toan vao 3 orbital dxy, dxz va dyz la nhng orbital khong tham gia taolien ket . Tuy khong co kha nang tao lien ket nhng chung lai co the tao thanhlien ket vi cac orbital trong p hoac d cua phoi t . Co hai loai lien ket : d-p vad-d. Theo Pauling, khi tao lien ket , nguyen t trung tam se cho electron, cacelectron nay se ien vao cac orbital p, d trong cua phoi t. Nh vay, ien tch amse c chuyen ngc lai t nguyen t trung tam en cac phoi t. Lien ket nayc goi la lien ket cho (Lien ket cho nhan: M L)

Thuyet lien ket hoa tr con cho phep noi trc kha nang phan ng cua phcchat. Kha nang phan ng cua phc chat chu yeu c xac nh bang phan ng trao

oi cac phoi t cua phc chat vi cac ion hay phan t khac trong dung dch. ieukien thuan li cho s trao oi la :

- Co s lai hoa ngoai- Co cac orbital d ben trong t do nguyen t trung tam

Trong trng hp lai hoa ngoai, lien ket cua phoi t vi nguyen t trung tamyeu hn so vi khi co s lai hoa trong.

V du: [Fe(NH3)6]2+ (lai hoa ngoai) co kha nang phan ng hn nhieu so vi

[Fe(CN)6]4- (lai hoa trong).

Khi co mat cac orbital ben trong t do th c che trao oi lai khac. Do co cacorbital t do nen phc chat co the ket hp vao mot tieu phan nao o trong dungdch. Sau o mot trong cac phoi t se b tach ra nhng cho cho tieu phan tren.

V du: hai phc chat sau:

[Cr(NH3)6]3+

3d 4s 4p



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[V(NH3)6]3+

3d 4s 4pth phc chat th hai co kha nang phan ng ln hn nhieu so vi phc chat au.

Nhc iem cua thuyet lien ket hoa tr:- Phng phap ch han che cach giai thch nh tnh- Khong co kha nang giai thch va tien oan quang pho cua phc chat- Khong giai thch c ve mat nang lng tng oi cua lien ket oi vi

cac cau truc khac nhau

u iem cua thuyet lien ket hoa tr:- Ro rang, de hieu, cho phep giai thch cac cau hnh khong gian khac nhau

cua phc chat da tren khai niem lai hoa cac AO.- Phng phap a noi len c tnh chat cho-nhan cua lien ket, kha nang

tao lien ket khac nhau, giai thch kha nang phan ng , tnh chat t cuaphc chat.

2. Thuyet trng tinh the

Thuyet trng tinh the thc chat la thuyet tnh ien co ien co them nhng giaithch mang tnh chat lng t. Xuat phat t 3 iem c ban sau:

a- Phc chat ton tai c mot cac ben vng la do tng tac tnh ien gia iontrung tam va cac phoi t.b- Khi xet ion trung tam co chu y en cau tao electron chi tiet cua no, con oivi cac phoi t th ch coi chung nh la nhng ien tch iem (hoac lngcc iem) tao nen trng tnh ien ben ngoai oi vi ion trung tam. ongthi phoi t nay khac phoi t kia ch ai lng (o ln) cua trng o mathoi.

c- Cac phoi t phoi tr quanh ion trung tam tren cac nh cua hnh a dien, taonen cac phc chat co oi xng nhat nh.

Ngoai ra khi mo ta phc chat ngi ta ap dung cac nh luat cua c hoc lng

t.a. S tach mc nang lng va cac so hang trong trng phoi t

Cac phoi t tch ien tao nen trng tnh ien ben ngoai se gay anh hngen cau tao electron cua ion trung tam. Hieu ng chu yeu cua anh hng o laviec tach cac mc nang lng (cac orbital d) va cac so hang cua ion trung tam.Trong c hoc lng t, nguon goc cua s tach o goi la hieu ng Stark. Davao nhng khai niem ve ly thuyet nhom oi xng ngi ta co the xac nh ccach tach cac so hang nguyen t trong cac trng hp khac nhau.

Trc het chung ta xet trng hp n gian nhat : Phc chat Ti(H2O)63+ co

cau hnh bat dien eu, Ti 3+ co cau hnh 3d1. Vi ML = 2, MS= 1/2, so hang cban la 2D.



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trang thai t do, cac orbital d la nhng orbital suy bien: ca 5 orbital conang lng nh nhau. Khi co anh hng trng tnh ien cua cac phoi t thmc suy bien se giam i. S ay tnh ien gia cac electron d va cac phoi tam ien (hay au am cua phan t lng cc) se lam tang nang lng cacorbital d

x

2-y

2 va dz

2 hng en cac phoi t va lam giam nang lng cac orbitaldxy, dxz, dyz, hng gia cac phoi t.

E eg (dx2-y2 , dz2)

d t2g (dxy, dxz, dyz)

Ion t do Bat dien eu (Oh)

Nh vay so hang 2D suy bien bac 5 cua ion t do khi trong trng bat diencua cac phoi t b tach thanh 2: so hang 2T2g suy bien bac 3 va so hang 2Eg suybien bac 2.

2D 2T2g + 2Eg

Mot so khai niem can biet cua ly thuyet nhom:- Cac ch cai thng a, b, e, t thng c dung e mo ta cac orbital mot

electron (hoac cac ham song) c phan loai theo kieu oi xng nhatnh.

- Cac ch cai hoa A, B, E, T ch nhng trang thai nhieu electron thuoc cungkieu oi xng.

- Cac ky hieu nay cho biet mc suy bien. Trang thai ky hieu a, A, b, B latrang thai khong suy bien (mc suy bien bang 1). Trang thai ky hieu la e,E, t, T la trang thai suy bien bac 2 va 3 tng ng.

- Cac ham a, A khong bien oi dau khi quay quanh truc oi xng bac n motgoc 2/n. Cac ham b, B co s bien oi dau.

- Ky hieu g ch nhng ham khong oi dau khi thc hien phep nghch aoqua goc toa o. Con ky hieu u ch nhng ham co s oi dau.- Ch so 1 va 2 thng c dung e ch s khac nhau oi vi mat phang

chieu.



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S tach mc nang lng d va cac so hang trong trng t dien khac vitrng bat dien (ngc lai):

E t2g (dxy, dxz, dyz)

d eg (dx2-y2 , dz2)

Ion t do T dien eu ( Td )

Trng oi xng bat dien eu va t dien eu la trng oi xng cao (trng

lap phng). Trong cac trng oi xng thap hn: bat dien keo dai truc z hoacvuong phang , cac mc nang lng va so hang lai b tach tiep tuc.

Khi ion trung tam co 2 hoac nhieu hn electron th cach tach cac so hang sephc tap hn. Ngi ta ap dung quy tac tng ng. V du , xet cau hnh d 9, vehnh thc co the coi nh lp vo kn d10 con 1 lo khuyet tch ien dng. Do os o tach cac so hang cua d 9 giong ve thanh phan nhng trat t ngc lai vid1

2D 2Eg + 2T2g

Quy tac tng ng nay c ap dung cho cac cau hnh khac nhau nh sau:

Giong nhau : dn va d5+n

Ngc nhau : dn va d10-n

Nh vay ch can biet them s tach cua cau hnh d2 la co the suy ra oi vicau hnh khac: d2, d7 va d8.

S o tach cua so hang F (cau hnh d2 va d7 ):

F T1g + T2g + A2g

Con so hang c ban cua he d5 va d10 khong suy bien nen trong trng phoi t

chung khong b tach.b. Cng o cua trng phoi t:

ion trung tam t do, khi cau hnh electron d co nhieu hn 1, th vai tro chuyeu la tng tac cua cac electron d vi nhau. Con trong phc chat, ngoai anhhng cua cac electron d, trng phoi t con tac ong len cac electron nay.Di anh hng cua trng nay, cac trang thai cua ion trung tam se b bien oi.



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Co 2 trng hp:

i.Trng hp trng yeu:Bang sap xep cac orbital d va trang thai c ban cua cau hnh e trong trng bat

dien:

So e Trang thai Cau hnh e (Oh) Trang thai S

c ban t2g eg c ban (Oh)

d1 2D 2T2g 1/2

d2 3F 3T1g 1

d3 4F 4Ag 3/2

d4 5D 5Eg 2

d5

6

S 6

A1g 5/2d6 5D 5T2g 2

d7 4F 4T1g 3/2

d8 3F 3A2g 1

d9 2D 2Eg 1/2

d10 1S 1A1g 0

Khi cng o cua trng phoi t nho (trng yeu) th cac so hang cua ion trungtam (phan loai theo momen ong lng toan phan L) van c gi nguyen, moilien he gia cac electron d khong b pha huy va so hang vi spin cc ai van la sohang c ban.

Nh vay, phc chat ng vi trng yeu laphc chat spin cao hayspin t do.

ii.Trng hp trng manh:Khi anh hng cua trng phoi t u manh th anh hng o vt xa tng tac

tnh ien gia cac electron d. Khi o, s sap xep cac electron d se khac. Thc tes khac nhau ch xay ra cac cau hnh d4 en d7.

d4 5D 3T1g 1

d5 6S 2T2g

d6 5D 1A1g 0

d7 4F 2Eg 1/2

Trong trng manh spin toan phan cua he thap hn so vi trng yeu, nen cacphc chat c goi laphc chat spin thap hayspin ghep oi.

iii.Thong so tach:oi vi trng hp 1 electron d ion trung tam co the ac trng cho s tach 2

mc nang lng eg va t2g bang mot ai lng goi la thong so tach (ky hieu la



20/64


hoac 10Dq) la hieu so gia 2 mc nang lng. cac trng hp phc tap hn (soelectron d nhieu hn mot), mot cach gan ung cung co the dung ai lng thongso hoac 10Dq ac trng cho s tach.

Co the tnh c thong so tach vi s gan ung cua thuyet trng tinh the theo

cong thc:5eqa4

hoac 10Dq = ______________

3r5

hoac:

5ea4

hoac 10Dq = ______________

r5

e- ien tch ion trung tam

q- ien tch cua phoi t

- momen lng cc cua phoi t

r- khoang cac t tam ion en tam phoi ta- ban knh trung bnh cua cac orbital d

Co the xac nh bang thc nghiem khi nghien cu quang pho hap thu electroncua phc chat. phu thuoc mot so yeu to sau:

- Kch thc ion trung tam r- ien tch cua ion trung tam Z

= KZ2r2 , trong o K la he so ty le

- Cau truc cua ion trung tam- Ban chat cua phoi tBang thc nghiem ngi ta sap xep cac phoi t tao phc theo th t tang va

goi laday quang pho hoa hoc:

I-< Br-< Cl- SCN-< NO3-< F-< TiO OH-< H2O < Py NH3< NO2-< CN-

Trong trng bat dien va t dien, thong so tach c ky hieu la O va T tngng, T = 4/9 O (trong cung ieu kien).

oi vi nhng phc chat co oi xng khong phai la lap phng th hnh anhtach kha phc tap nen khong the ac trng cho s tach bang mot thong so.

c. Nhng he qua cua hien tng tach:

i.Tnh chat on nh cua he phc chatTrong ion phc, cac electron cua ion trung tam phan bo tren cac orbital co nang

lng thap trc, v vay he tiet kiem c mot nang lng va gia tr o c goilanang lng on nh bi trng tinh the.



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V du: Trong trng bat dien:

O = ED - Et2g = 0,4 O

Con trong trng t dien th T = ED - Eeg = 0,6 T va trong nhng ieu kien nh

nhau th T = 2/3OKhi ion trung tam co nhieu electron d th o ben toan phan se bang tong o

ben cua moi electron a vao. Chu y la moi electron ien mc thap th lam chohe on nh mot gia tr nang lng tng ng va ngc lai.

Bang 3: Gia tr nang lng on nh bi trng tinh the

oi vi phc chat bat dien va t dien theo n v O

Cau hnh e V du Phc chat spin cao Phc chat spin thap

Oh Td Oh Td

d0 Ca2+,Sc3+ 0 0 0 0

d1 Ti 3+ 0,40 0,27 0,40 0,27

d2 V3+,Ti2+ 0,80 0,54 0,80 0,54

d3 Cr3+,V2+ 1,20 0,36 1,20 0,81(1)

d4 Mn3+,Cr2+ 0,60 0,18 1,60(1) 1,07(2)

d5 Mn2+,Fe3+ 0 0 2,00(2) 0,89

d

6

Fe

2+

,Co

3+

0,40 0,27 2.40(3) 0,71d7 Co2+,Ni3+ 0,80 0,54 1,80 0,54

d8 Ni2+ 1,20 0,36 1,20 0,36

d9 Cu2+ 0,60 0,18 0,60 0,18

d10 Zn2+,Cu+ 0 0 0 0

Co the thay c tnh chat on nh bi trng tinh the qua s lien he vi cactnh chat nhiet ong cua phc chat nh nang lng hydrat hoa, nang lng taophc, nang lng mang li,.

V du: Phan ng hydat hoa cac ion kim loai hoa tr 2 day chuyen tiep th nhat:

M2+(k) + nH2O [M(H2O)6]2+ (aq) + H0



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23/64


CuF2, 2 lien ket Cu-F 2,27 Ao va 4 lien ket 1,93 Ao. Trng hp ti han dan envuong phang. Nh vay, o suy bien cua he giam i. Hieu ng nay c goi la hieung Ian-Tel vi nh ly nh sau: Trang thai electron suy bien cua he phan tkhong oi xng bat ky la trang thai khong ben, v the he o phai chu mot s sailech nao o e cho tnh oi xng cung nh mc suy bien cua no giam i.

Trong trng hp Cu2+, vi s sap xep tren, he tiet kiem c mot nang lng1/2. Cac trng hp khac chung ta xet mot cach nh tnh:

Trong trng bat dien:- Khong sai lech cau hnh: e phan bo oi xng cau

Phc chat spin t do: t2g0, t2g3, t2g3eg2 t2g6eg2 t2g6eg4

Phc chat spin ghep oi: t2g0, t2g3, t2g6 t2g6eg4

- Sai lech t: Neu tren cac orbital t2g co 1,2,4,5 ePhc chat spin t do: t2g

1

, t2g2

, t2g4

eg2

t2g5

eg2

Phc chat spin ghep oi: t2g1, t2g2, t2g4 t2g5

- Sai lech nhieu: Neu tren cac orbital eg cha 1,2,3 ePhc chat spin t do: t2g3eg1 t2g6eg3

Phc chat spin ghep oi: t2g6eg1 t2g6eg2 t2g6eg3

Nhng ket luan tren ap dung cho phc chat co cac phoi t ong nhat, con oivi cac phc chat co cac phoi t khac nhau th ban than cac phoi t a gay ra sbien dang roi.

Quang pho hap thu cua phc chatThanh cong ln nhat cua thuyet trng tinh the la giai thch c mau sac

(quang pho) cua phc chat. Quang pho hap thu cua phc chat c gay ra binhieu nguyen nhan: chuyen dch d-d, quang pho cua phoi t, ion cau ngoai,ay ta ch xet s chuyen dch d-d.

V du: xet quang pho hap thu cua he d1: phc chat Ti(H2O)63+

Quang pho cua phc chat nay co mot giai hap thu yeu vi cc ai hap thu 4900 A0 (hoac 20.400 cm-1). Theo thuyet trng tinh the th s hap thu o la ket

qua kch thch electron duy nhat cua Ti3+ t mc t2g len mc eg. Dung dch phcchat hap thu cac tia vang cho cac tia con lai i qua to hp vi nhau thanh mau tm.



24/64


(A0)=>

3000 4000 5000 6000

25 30 25 20 15 10


25/64


oi vi he d9 (so hang 2D) cung co mot bc nhay t 2Eg len 2T2g va ta cungco mot vach hap thu. That vay, phc chat [Cu(H2O)6]

2+ co mot giai hap thurong 12.600 cm-1 con phc chat [Cu(NH3)6]2+ 15.100 cm-1.

T1g(P) T1g(P)

T1g(F) P A1g

T2g F T2g

A1g T1g(F)

d3,d8 (Oh) d2, d7 (Oh)

d2,d7 (Td) d3, d8 (Td)

Quang pho hap thu phc chat con phu thuoc vao 2 quy tac loc la sau ay:1- Nhng bc nhay gia cac trang thai co o boi spin khac nhau b cam

(khi chuyen trang thai so electron oc than khong c thay oi)- Quytac spin.

2- Khi phan t co tam oi xng th s chuyen noi bo mot phan lp d cung bcam - Quy tac Laporte.

Quy tac nay hoan toan nghiem ngat oi vi ion t do nhng trong phcchat co the b vi pham.

Nh vay, trong phc chat bat dien (co tam oi xng), cac bc nhay d-d sela nhng bc nhay yeu va nhng bc nhay b cam ve spin lai cang yeu hnna. Trong khi o, phc t dien, khong co tam oi xng, bc nhay d-d manhhn hang tram lan.



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V du: [Co(H2O)6] 2+ mau hong, [CoCl4] 2- xanh am.

4P4T1g

4D4Eg

4T2g4G4Eg4A1g

4T2g

4T1g6S4A1g

d5 => (Oh)

T nhng ieu tren, chung ta thay rang mot giai duy nhat phat hien c cuaphc chat [Ti(H2O)6]

3+ trong vung quang pho trong thay s d co cng o nhov no c gay ra bi bc nhay b cam theo quy tac Laporte.

oi vi phc chat bat dien cua V3+ (d2) va Co2+ (d7) s o Orgel noi trc coba bc nhay c phep ve spin sau ay:

3T1g => 3T2g3T1g (F) =>

3T2g (P)3T1g => 3T2g

Thc nghiem a xac nh c ba cc ai ng vi ba bc nhay tren, trongo co hai cc ai vung trong thay va mot vung t ngoai. V du, cua[V(H2O)6]3+ tng ng la 17.700, 25.000 va 35.000 cm-1

oi vi cac phc chat cua cac cau hnh d3, d8 cung co ba bc nhay. Pho cuaphc chat Cr3+ rat ly tng, khi thay the cac phoi t khac nhau ngi ta thuc day quang pho hoa hoc.



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oi vi phc chat cua ion Mn2+ (cau hnh d5), v du: [Mn(H2O)6]2+ quang phocua chung co nhieu vach, co cng o be v chung va b cam ve spin va vetnh oi xng.

Ket luan: Ngoai nhng thanh cong tren, thuyet trng tinh the cung con

mot so han che (do han che cua luan iem th hai):Khong mo ta c lien ket cong hoa tr, lien ket kep. Do o khong mo ta

c toan bo cac phc chat nh phc chat cacbonyl, nitrozyl,

3. Thuyet ORBITAL Phan t (OP hay MO- molecular orbital)

Theo thuyet MO, cac electron phan bo tren cac orbital chung cua phan t. Viectm ham song, ngha la viec giai phng trnh Schroedinger oi vi he phan t larat kho khan ma phai giai gan ung nh sau:- Gia thiet a so cac electron khong tham gia tao thanh cac MO ma nh cho tai

cac hat nhan rieng re, ch cac electron hoa tr ben ngoai hoac mot phan cacelectron o mi tham gia.- Cac MO c tao thanh nh s to hp tuyen tnh cac AO (Phng phap gan

ung MO-LCAO).

a. Xet s tao thanh cac MO

Xet phc chat bat dien MA6 :

Ham song trong phc chat bat dien co dang:

= a0 + b

Trong o: 0 la AO cua ion trung tam,

la MO cua he gom 6 phoi t: = c11 + c22 + ... + c66

i la AO cua phoi t th i. Neu phoi t lai la he nhieu nguyen t th se laMO cua chung. Tren thc te, e n gian, ngi ta coi i la mot AO tng ngnao o cua nguyen t gan ion trung tam nhat.

a, b, c1,.c6 la nhng he so can xac nh.

Cac o va phai thuoc cung kieu oi xng mi to hp c thanh cac MOcua phc chat.

Co 2 trng hp :- oi xng : Neu moi i oi xng vi ng lien ket th orbital va

c goi la orbital . Cac i c ky hieu la i- oi xng : Neu moi i oi xng vi mat phang lien ket th orbital

va c goi la orbital . Cac i c ky hieu la i

Ta co the viet bieu thc cac ham song lien ket ng vi to hp cong va phanlien ket ng vi to hp tr nh sau:

slk , I = c14s + c2 (1 + 2 + 3 + 4 + 5 + 6)

s* , I* = c14s - c2 (1 + 2 + 3 + 4 + 5 + 6)



28/64


xlk , II = c3px + c4 ( 3 - 4)

x* , II* = c3px - c4 ( 3 - 4)

ylk , III = c5py + c6 ( 5 - 6)

y* , III* = c5py - c6 ( 5 - 6)

zlk , IV = c7pz + c8 (1 - 2 )

z* , IV* = c7pz - c8 (1 - 2)

z2 lk , V = c9dz2 + c10 (21 + 22 - 3 - 4 - 5 - 6)

z2 * , V* = c9dz2 - c10 (21 + 22 - 3 - 4 - 5 - 6)

x2-y2 lk , VI = c11dx2-y2 + c12 (3 + 4 - 5 - 6)

x2-y2 * , VI* = c11dx2-y2 - c12 (3 + 4 - 5 - 6)

T o ta co gian o nang lng cac MO cua phc chat MA6. Cac AO kieu t2gkhong thuoc oi xng c a vao di dang khong lien ket.

Viec ien electron vao cac MO: Moi phoi t co 2 e , con ion trung tam co ne tren AO d se ien vao t2g va e*g. No phu thuoc vao nang lng ghep oi P (lanang lng can thiet e chuyen e t trang thai ma o chung chiem 2 orbital conang lng ong nhat vi spin song song len trang thai co spin oi song trencung mot orbital) va khoang cach nang lng = Ee*g - Et2g

Khi n < 3 th cac e chiem cac MO t2g, con khi n > 3 th co 2 kha nang:- Neu > P th cau hnh se theo kieu ghep oi (phc chat spin thap)- Neu < P th cau hnh se theo kieu t do (phc chat spin cao)

b. Cac MO

Xet phc chat bat dien MA6:

oi vi ion trung tam ngoai cac AO a tham gia to hp MO ch con co 3 AOkieu t2g co the to hp cac MO . Cac phoi t co the dung cac AO p hoac d(hoac cac MO tng ng) e tham gia to hp, thng la cac AO p.

Do s tao cac MO ma gian o nang lng co thay oi. Xet 2 trng hpthng xay ra:a. Cac orbital cua phoi t a bao hoa electron va ben hn (nang lng thap

hn) so vi AO t2g cua ion trung tam: F-, OH-,b. Cac orbital cua phoi t con trong va kem ben hn (nang lng cao hn) so

vi AO t2g cua ion trung tam: PH3, AsH3, CO, CN-



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E*g

'

T2g

E thap, bao hoa e

E cao, con trong

E*g

'

T2g

Trng hp a Trng hp b

Nh vay, vi viec hnh thanh cac MO va , thuyet MO a khac phuc ccac thieu sot ma cac thuyet trc cha giai thch c (ve hnh thc hnh anhtach cac AO d thuyet trng tinh the c the hien thuyet MO nhng banchat la khac nhau).



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Chng IV. CAC PHNG PHAP NGHIEN CU PHCCHAT

e nghien cu phc chat ngi ta s dung 2 nhom phng phap chnh:I. PHNG PHAP TONG HP NGHIEN CU PHC CHAT

Co the s dung cac phng phap hoa hoc va hoa ly:1- Phng phap hoa hoc:2- Phng phap hoa ly:

a- Phng phap o o dan ienb- Phng phap nghien cu cau truc bang tia Xc- Phng phap t hoa hocd- Phng phap nhiet ky

II. CAC PHNG PHAP NGHIEN CU PHC CHAT TRONG DUNG DCH

Phng phap tong hp nghien cu phc chat la phng phap pho bien, ac biettrong giai oan au cua viec nghien cu phc chat. Hoa hoc phc chat phat trienc la da vao viec ap dung phng phap tong hp: tong hp cac phc chat miva nghien cu cau tao cua chung.

Tuy nhien phng phap tong hp khong cho chung ta hieu biet ve tnh chat cuacac dung dch phc chat ma no lai co vai tro quan trong trong viec nghien cu, ng

dung phc chat vao cac lnh vc thc tien.V du: phng phap tong hp khong phan biet c muoi kep va phc chat.

o ben cua phc chat trong dung dch:

ac trng cho dung dch phc chat la 4 dang can bang sau:a- S ien ly phc chat thanh ion phc va ion cau ngoaib- Can bang phan ly cua ion phcc- S phan ly cua phoi td- Can bang oxyhoa - kh

Chung ta ch xet 2 dang can bang au (ac biet la can bang th hai):V du:

Cu(NH3)42+ Cu2+ + 4 NH3

Fe(CN)63- Fe3+ + 6 CN-



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Thc chat la cac ion b hydrat hoa.

S phan ly xay ra khong ang ke va tuan theo nh luat tac dung khoi lng.

[Cu2+][NH3]4

K = --------------------- = 4,6.10-14[ Cu(NH3)42+]

[Fe3+][CN-]6

K = ---------------------- = 1,0.10-44

[ Fe(CN)63-]

V K ac trng cho o ben cua ion phc trong dung dch nen no c goi la

hang so khong ben va nghch ao cua no la hang so ben hay hang so tao thanh=1/K

Khi co s tao phc bac th ng vi moi bac ta co hang so ben hoac khongben tng bac tng ng:

K = k1.k2.kn

= 1.2n

Hang so khong ben la mot ai lng quan trong, nhng gia tr cua no khacnhau neu chung ta s dung nong o can bang C. Muon chnh xac phai dung ailng hoat o can bang a.

Nghien cu phc chat trong dung dch la xac nh thanh phan va hang sokhong ben (hoac hang so ben) cua ion phc. Xet 2 phng phap:

1.Phng phap ien the

Thc chat cua phng phap la o the can bang phat sinh gia kim loai vadung dch, neu s phat sinh ien the o lien quan vi qua trnh can bang:

M = Mn+ + ne

Tren thc te ngi ta thiet lap mach nong o sau:

(-) M/ Mn+(dd)// Mn+(dd)/ M (+)

1 C1 C2 2

Khi o sc ien ong cua mach nong o se la:

E = 2 - 1 = RT/nF ln C2/C1

E c xac nh bang thc nghiem, khi biet C1 ta co the xac nh c C2 la

nong o cua ion t do trong dung dch co s tao phc. Co hai kha nang nghien cus tao phc:



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Xac nh nong o ion kim loai t do

Xac nh nong o phoi t t do neu co can bang: An- = A + ne

Trong nhieu trng hp neu co ieu kien th co the xac nh ca hai loai nongo o.

a. He tao thanh mot phc chat

i.Phc chat mot nhan:Gia s qua trnh tao thanh phc chat mot nhan theo s o sau:

M + nA MAn

[M][A]n

K = ------------- (1)

[MAn]Neu tien hanh th nghiem vi ieu kien : CA >> CM >> C , trong o:

CA- nong o ban au cua phoi t A

CM- nong o ban au cua ion kim loai M

C- nong o can bang cua ion kim loai M

Th: [M] = C, [MAn] = CM - C CM, [A] = CA - nCM CA

Khi o:

C. CAn

K = ------------ (2)

CM

Lay logarit 2 ve cua (2) ta co:

Lg CM /C = n lg CA - lg K (3)

Neu c che gia thiet tren la ung th o th trong he toa o lg CM/C - lg CAse la mot ng thang co he so goc la n va oan cat truc tung bang -lg K.

Khi lam th nghiem, pha mot day dung dch co CM = const, con CA thay oi.Sau khi xac nh E cua cac mach nong o, tnh nong o can bang cua ion kim loaitrong moi dung dch va ve o th theo phng trnh (3).



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lg CM/C

- lgK

lgCA

Hnh 3: S phu thuoc lgCM/C vao lgCA

Bang phng phap nay, ngi ta a xac nh c thanh phan va hang sokhong ben cua cac phc chat. V du: Trong cac he Ag+ - I- , Pb2+ - I- , he au dungien cc Ag - AgI32- co K = 1,6.10-4, he sau dung ien cc hon hong ch - PbI42- coK = 10-7.

ii.Phc chat nhieu nhan:Gia thiet qua trnh tao phc xay ra theo s o:

qM + rA MqAr

[M]q[A]r

K = ------------- (4)

[MqAr]

[MqAr]

T o : [M]q = K ---------------- (5)

[A]r

Sc ien ong cua mach nong o la:

RT [MqAr]2 [A]1r

E = --------- ln --------------------- (6)

qnF [MqAr]1 [A]2r



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Neu lay 2 dung dch cha ion kim loai M co nong o khac nhau va cungmot lng d phoi t A th :

RT [MqAr]2

E = --------- ln -------------- (7)

qnF [MqAr]1

Neu phc chat kha ben va lay rat d phoi t th thc te co the coi nh tatca ion kim loai i vao phc chat. Khi o: [MqAr]1 = CM1 , [MqAr]2 = CM2 va:

RT CM2

E = ---------ln--------------------- (8)

qnF CM1

Bieu thc nay cho phep tnh q.

Tng t, khi so sanh 2 dung dch co cung nong o ban au cua ion kimloai va nhng lng d khac nhau cua phoi t, ta co :

rRT CA1

E = ---------ln---------- (9)

qnF CA2

T (9) xac nh c r. Thay cac gia tr nong o can bang, q, r vao phngtrnh (4) xac nh c K.

b. He tao phc bac (phc chat mot nhan)

Co 2 phng phap nghien cu phc chat bac la phng phap Berum vaphng phap Leden. ay ta xet mot phng phap Leden nh sau:

Gia thiet cac qua trnh xay ra nh sau:

[MA]M + A MA 1 = ------------

[M] [A]

.

MAN-1 + A MAN



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Gia s CM , CA la nong o ban au cua M va A, theo nh luat bao toan khoilng ta co :

CM = [M] + [MA] + [MA2] + + [MAN]

CA = [A] + [MA] + 2[MA2] + + N[MAN]

Hay:

CM = [M] + 1[M][A] + 2[M][A]2 + ..+ N[M][A]N

CM-[M]

---------- = 1[A] + 2[A]2 + ..+ N[A]N

[M][A]Da vao bieu thc nay e tnh toan 1 , 1 ..Viec tnh toan c tien

hanh theo phng phap gan ung lien tuc nh sau:

Tnh gia tr :

CM-[M]

F0[A] = ----------

[M][A]

oi vi cac gia tr nong o can bang khac nhau cua phoi t roi ngoai suy en [A]= 0 theo o th, xac nh c 1.

F0[A]

1

[A]

Sau o tnh F1 = F0 -1 /[A] theo [A] khac nhau, roi tnh 1



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e tnh F0[A] theo cong thc tren, can phai biet nong o cua ion kim loaiva phoi t t do. c xac nh trc tiep bang phng phap ien the. Neu CM nhova o ben phc chat be th co the coi:

[A] CA

Trong trng hp chung, [A] # CA nen phai xac nh theo cach khac.

Theo Leden, vi s gan ung cap 1 co the xac nh [A] nh sau : Gia strong he khong tao phc chat bac ma tao thanh mot phc chat MAN nao o. Phcchat gia nh nay cho cung nhng gia tr va [A] nh khi tao phc chat bac.

[MAN]

M + NA MAN = ------------

[M] [A]N

So phoi tr cua phc chat o c xac nh t phep o ien the nh sau:

E = RT/nF ln [M] + const

Neu phc chat kha ben th co the coi rang khi CM khong oi th MAN khongoi va v vay, bieu thc tren co the viet :

E = - RT/nF N ln [A] + const

Tien hanh o sc ien ong hai gia tr CA1 va CA2 hai th nghiem co the

xac nh c N t phng trnh :E2 - E1 = RT/nF N ( ln [A]1 - ln[A]2 )

= RT/nF N (ln CA1 - ln CA2 )

ay vi s gan ung co the coi CA = [A] . Mat khac Leden coi rang N la ty sogia so phoi t va so ion kim loai trong phc chat:

n [MAn]

N = ----------------

[MAn]

T o ket hp vi phng trnh tnh CA, CM tren ta co phng trnh cho phep

tnh :

[A]= CA - N (CM -[M] )

cac gia tr c dung e xac nh 1 , 2 , qua F0 [A] , F1[A] vi s gan ungcap 1. Sau khi xac nh c cac gia tr 1 , 2 , n th tien hanh chnh xachoa ai lng N, roi lai tnh cac hang so cho en khi gia tr cac hang so khong b

thay oi na.



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N c chnh xac hoa theo phng trnh :

n n[A]n-1

N = ----------------

n[A]n-1

2.Phng phap trac quang

Phng phap trac quang la mot bien dang cua phng phap phan tch hoa ly.C s cua phng phap la nghien cu cac kieu khac nhau cua gian o thanh phan-tnh chat. Trng hp thng gap la he 3 cau t : Ion trung tam M - Phoi t A -Dung moi S. Co the bieu dien he nay bang tam giac thanh phan.

Ss s

m

am a

M A

- Lat cat m-a tng ng vi day cac dung dch co lng dung moi nh nhau, CM vaCA khac nhau nhng CM + CA = const. Day dung dch nay c goi la day dungdch ong phan t.

- Lat cat m-s tng ng vi day dung dch co CA = const, CM thay oi.

- Lat cat a-s tng ng vi day dung dch co CM = const, CA thay oi.

Phng phap trac quang nghien cu mot lat cat nao o cua he va da tren cs sau ay:

a- Tnh chat c xac nh la mat o quang D cua dung dch. No cho biet s hapthu anh sang bi dung dch cha phc chat nghien cu. S hap thu nay tuantheo nh luat Lambe-Bia :

D = lg I0 /I = Cl

D: mat o quang bc song

I0: cng o anh sang ti (n sac)I : cng o anh sang sau khi i qua dung dch



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I/I0 = T la o truyen qua

C: nong o phc chat trong dung dch

: hang so ac trng cho mot chat xac nh va c goi la he so hap thuphan t

nh luat Lambe-Bia la co gii han, no ch ung oi vi cac dung dch, anhsang co cac ieu kien sau ay:

- Chum anh sang phai n sac

- Dung dch phai kha loang C < 10-2 M

- Phai la dung dch that (khong ap dung cho dung dch phat huynh quang vacac huyen phu).

D c xac nh bang cac may quang pho ke hoac gan ung bang cac sac

ke quang ienb- Mat o quang D la ai lng cong tnh. Neu trong dung dch co mot so phan thap thu anh sang co cac nong o C1, C2,Cn th D tong cong se la:

D = D1 + D2 + .. + Dn = (C1 + C2 ++ Cn)l

Nhiem vu quan trong la phai tm phan mat o quang cua chat ma ta can xacnh, v du phc chat MAn:

Di = MAn . CMAn .l

Bang cach tien hanh phep o vung bc song ma he so hap thu phan tcua cac chat khac nhau nhieu nhat, tot nhat la ch mot mnh phc chat hap thu.

a. Phng phap day ong phan t (lat cat m-a)

i.Xac nh thanh phan:e xac nh trong he tao thanh may phc chat, chung ta nghien cu quang

pho hap thu cua nhng dung dch cha ion kim loai va phoi t tao phc nhng tyle khac nhau. Thng thng pha mot day dung dch trong o CM = const, CA tangdan. Neu ng cong hap thu, bieu dien s phu thuoc D - CA/CM cua cac dungdch o tng t nhau th chng to ch tao thanh u the mot phc chat. Sau o xay

dng ng cong hap thu cua cac dung dch vi ty le CA/CM = const cac pH khacnhau. Neu ch tao thanh mot phc chat th cac ng cong o cung phai tng tnhau. (Coi M va A khong hap thu anh sang).

Gia s phan ng tao phc MAn nh sau:

M + nA MAn

Khi o hang so ben cua phc chat la:

[MAn]

= ------------

[M] [A]n



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Can xac nh n, ngha la xac nh thanh phan cua phc chat. Ngi ta dungphng phap day ong phan t Oxtromxlenxki-Zop (Con goi la phng phap bienthien thien tuc).

Day ong phan t, tng ng vi lat cat m-a, la mot day dung dch co tong

nong o CM va CA khong oi nhng ty le CA/CM thay oi.Xac nh D bc song ch mot mnh phc chat hap thu roi dng gian o

thanh phan - D. Gian o nay la mot ng cong co cc ai. Tai D cc ai, ng vity le CA/CM ma o cac cau t tng tac vi nhau hoan toan tao thanh phc chat,ngha la CA/CM = n .

Cach pha day dung dch ong phan t: Lay 2 dung dch A va M co nong obang nhau, sau o tron chung lai vi nhau vi ty le the tch khac nhau nhng VA +VM = const

Dmax

CM CA

e lam chnh xac them v tr cua cc ai hap thu, can phai pha them motday dung dch co ty le the tch thay oi hep hn xung quanh iem ng vi D max.ieu nay ac biet can thiet khi cc ai cua ng cong hap thu khong nhon (dophc chat kem ben) hoac khi thanh phan cua phc chat khac nhieu vi ty le 1/1 laty le n gian nhat.

Trng hp tong quat, gia s he tao thanh phc chat MmAn :

mM + nA = MmAn

Can phai chng minh rang thanh phan cua phc chat ng vi ty le cau ttron vi nhau v tr D cc ai: nhng dung dch khong ng vi iem cc ai,ham lng phc chat tao thanh be, nen co the coi [A ] = CA va [M] = CM. V vay taco:

[M]m[A]n CMm CAn

K = ---------------- = ----------------- , y la lng phc chat tao thanh

[MmAn] y



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Lay logarit 2 ve va lay vi phan:

Ln y = m ln CM + n ln CA - ln K

dy/y = mdCM/CM + ndCA/CA = 0

Mat khac lay vi phan phng trnh CM + CA = const ta co dCM + dCA = 0 hay:

dCM = - dCA . Thay vao tren ta co:

-mdCA/CM + ndCA/CA = 0 hay m/CM = n/CA hay m/n = CM/CA

Ro rang la cac ty le CA/CM khac nhau va CM + CA = const th ham lngcua phc chat cc ai theo ung ty le hp thc.

Ta con co : x = CA/CM + CA va xmax = n/m+n

Khi dng gian o thanh phan - D can chu y cac iem sau ay:

- Gia tr pH cua cac dung dch can c gi khong oi e on nh qua trnh thuyphan cua ion kim loai va qua trnh proton hoa phoi t (neu cac qua trnh nay xayra) vi cung mot mc o. pH can phai co gia tr toi u e am bao hieu suat taophc cc ai.

- Neu ieu kien th nghiem ma ion kim loai co the ket hp vi phan t X naoay thanh phc chat MXn th trong tat ca cac dung dch cua day eu phai lay motlng X nh nhau.

- Lc ion cua dung dch ong phan t phai nh nhau.

- Ngoai phc chat con co cac cau t M va A cung hap thu anh sang bc songa chon th mat o quang cua dung dch o c la gom mat o quang cua tat ca.Khi o muon gi c moi lien he tuyen tnh gia nong o phc chat vi tnh chatD can phai lay gia tr hieu so :

D = D - D0

D0 la tong mat o quang cua cac dung dch cha A va M vi nong o bangnong o cua chung trong dung dch khao sat.

That vay, D la mat o quang cua dung dch khi l=1) se gom:

D = DM + DA + DMmAn = M[M] + A[A ]+ MmAn[MmAn]

D0 = ACA + MCM

CA = [A ]+ n [MmAn]

CM = [M] + m[MmAn]

Thay cac gia tr vao D se co :

D = (MmAn - nA- mM) [MmAn]

(MmAn - nA- mM) la hang so nen D ty le vi nong o phc chat tao thanh.



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Phng phap day ong phan t khong phai la phng phap thong dung, noch ap dung c cho nhng he tao thanh mot phc chat va co mot so nhc iem:

+ Rat kho xac nh iem cc ai khi ng cong co dang tu (phc chat kem ben)

+ Ch ap dung tot cho cac trng hp tao thanh cac phc chat co so phoi tr n = 1,

2, 3 vi xmax = 50% ; 66,6% va 75% con cac phc chat co so phoi tr cao n = 4, 5 va6 th v tr cc ai gan nhau nen rat kho xac nh, xmax tng ng la 80% ; 83,3%va 85,5%.

+ Phng phap day ong phan t trong trng hp tong quat cho phep tm khong

phai la cac ch so trong cac cong thc cau tao cua phc chat nghien cu ma ch

cho ta ty so cua chung. No khong cho phep la chon gia nhng phan ng:

MA + B = MB + A

MA + B = MABHoac: M + A = MA

2M + 2A = (MA)2

ii.Xac nh hang so ben:Viec xac nh hang so ben cua phc chat lien quan en viec xac nh cac

he so hap thu phan t cua cac cau t M, A va phc chat.

Phng phap 1: S dung 2 iem bat ky cua ng cong D trong day ong phan t

V du : phan ng tao phc n gian :M + A = MA

Khi o:

[MA] C'p C''p

= ------------- = -------------------------- = -------------------------

[M][A] (C'A-C'p)(C'M-C'p) (C''A-C''p)(C''M-C''p)

trong o: Cp - nong o can bang cua phc chatCM, CA - nong o ban au cua M va A

Neu bc song a chon ch mot mnh phc chat MA hap thu anh sang th Cp =D/p (l = 1cm). Thay vao bieu thc tnh ta co:

D' D''

-------------------------- = ------------------------------

(C'A-D'/p)(C'M-D'/p) (C''A-D''/p)(C''M-D''/p)



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thay x = CA/(CA+CM) = CA/C ta co:

D' D''

-------------------------------- = ---------------------------------[Cx'- D'/p][C(1-x')- D'/p] [Cx''- D''/p][C(1-x'')- D''/p]

Giai phng trnh nay vi an so la p ta co:

D'D''2 - D''D'2

p = 1/C -------- --------------------

D''x'(1-x') + D'x''(x''-1)

Biet p ta tm c Cp va tnh c .

Phng phap 2: phng phap pha loang Bapco : Dung e xac nh cua phc chatco o ben trung bnh.

Pha mot dung dch gom cac cau t M va A theo ty le hp thc roi dungdung moi pha loang dung dch p lan. Luc o o phan ly cua phc chat tang len. omat o quang cua dung dch trc va sau khi pha loang. Mat o quang D cua dung

dch sau khi pha loang c o vi cuvet a c tang chieu day len p lan so vitrc. Khi o se co s sai lech 2 gia tr mat o quang. o sai lech tng oi la:

Dp - D1

= -------------

D1

D1 - mat o quang cua dung dch au

Dp - mat o quang cua dung dch sau khi pha loang p lan va tang chieu day

cuvet len p lan.

Biet D = Cpl. Neu o ien ly cua phc chat trong dung dch au la1 , controng dung dch a pha loang la p th:

Dp/D1 = 1-p / 1-1

Do o: Dp - D1 (1-p ) - (1-1 ) 1 - p

= ---------- = ---------------------- = -------------

D1 1- 1 1 - 1



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Khi 1


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b. Phng phap co nh nong o mot cau t, thay oi nong o cau t kia

Xay dng gian o D (D) - CA/CM (CM/CA) thu cng cong bao hoamat o quang.

D (D)

T0 CA/CMD (D)

CA/CMc. Xac nh thanh phan:

Ngi ta s dung cac phng phap rieng tuy thuoc vao o ben cua phcchat:

i.Phng phap logarit (Bent va French):Gia s phc chat tao thanh theo phan ng :

mM + nA MmAn

Phc chat nay ben va hoac kem ben.

Hang so khong ben cua phc chat :

[M]m[A]n

K= ----------------

[MmAn]

Hay :



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lg [MmAn] = mlg [M] + nlg [A] - lgK

Cac he so m, n c xac nh nh sau:

Neu gi [M] = const, [A] thay oi th lg [MmAn] se phu thuoc tuyen tnh

vao lg [A]. Gia s vung bc song nghien cu ch co phc chat [MmAn] hap thuanh sang th lg [MmAn] ty le vi lg D. Dng o th bieu dien s phu thuoc lg D - lg[A] th se c ng thang co o doc la n.

lg D

lgCA

Mat khac neu dng o th lg D - lg [M] khi [A] = const, [M] thay oi thcung thu c ng thang co o doc la m.

Neu o th thu c khong phai la ng thang th trong dung dch con cophan ng phu.

Muon xac nh cac nong o can bang cua M va A ta tien hanh nghien cu dung dch rat loang. V phc chat kem ben nen khi pha loang no phan ly manh,do o nong o can bang cua M va A co the coi bang nong o ban au cua chung.

[M] CM , [A] CA

Khi o: lg [MmAn] mlg CM + nlg CA - lgK va dng o th lg D - lg CM ,lg D - lg CA

ii.Phng phap ty le phan t :La phng phap chung nhat e xac nh thanh phan phc chat ben.

Xac nh D hoac D cua cac dung dch co ty le CA/CM khac nhau khi CM =const hoac ngc lai. Bieu dien d phu thuoc D - C A/CM thu c ng cong baohoa mat o quang. iem gay T tren ng cong se ng vi ty le cac he so hpthc iem TO. V T oi khi co oan cong nho nen ngi ta s dung phngphap ngoai suy.



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oi vi cac phc chat n nhan, ai lng CA/CM TO bang 1, 2, 3,conai lng CM/CA = 1; 0,5; 0,33; tng ng vi cac phc chat MA, MA2, MA3,

Trong trng hp phc chat nhieu nhan th cac ty le CA/CM thng khongphai la so nguyen.

Bang 4: Cac gia tr CA/CMva CM/CA oi vi cac phc chat a nhanThanh phan n/m = CA/CM m/n = CM/CA

M2A 0,5 2,0

M3A 0,33 3,0

M2A3 1,50 0,67

M3A2 0,67 1,50

iii.Xac nh hang so ben

+ Da vao ng cong bao hoa mat o quang

oi vi phc chat ben MmAn co the de dang tnh c hang so ben: Davao gia tr D ta xac nh p, ng vi gia tr D th toan bo ion kim loai a i vaophc chat, khi o [MmAn] = CM/m

D = p l = p CM /ml => p = mD/CMl

T p co the xac nh c nong o can bang cua phc chat bat ky iemnao tren ng cong (oan i len): [MmAn] = Di/p l = Cp. T o xac nh [M] va[A]

[MmAn] Cp

= ------------- = ----------------------------

[M]m[A]n (CM-mCp)m(CA-nCp)n

+ Phng phap Bapco oi vi phc chat n nhan kem ben

Tai 2 iem cua ng cong khi CM = const, CA thay oi co the viet bieuthc sau ay khi CA >> Cp (phc chat kem ben)

Phan ng tao phc:

M + nA = MAn

Khi o hang so ben cua phc chat la:

[MAn] Cp' Cp''

= ----------- = ------------------ = -------------------

[M][A]n (CM-Cp')(CA')n (CM-Cp'')(CA'')n



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Neu D Cp (ch phc chat hap thu anh sang) va D''/D' = p th t phngtrnh tren ta co:

CM[(CA'')n - p(CA')n]

Cp' = ---------------------------------

p[(CA'')n - (CA')n]

Biet Cp' co the de dang xac nh theo phng trnh tren. Neu cac cau teu hap thu anh sang th khi o p = D''/D'



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Chng V. ONG HOC VA C CHE PHAN NG THE PHOIT

I. NHAC LAI MOT VAI KHAI NIEM1. Toc o phan ng:

Toc o phan ng la bien thien nong o cua mot trong cac chat au hoac sanpham trong mot n v thi gian.

Gia s co phan ng : A + B => C

Th :

v = - dCA/dt = - dCB /dt = dCC/dt

Mat khac ta thay rang, toc o phan ng phu thuoc vao so tieu phan tham giaphan ng. So tieu phan cang nhieu, toc o phan ng cang ln. V vay ta co bieuthc cua nh luat tac dung khoi lng:

v = kCACB

Trong o :k- He so ty le =Hang so toc o phan ng

CA, CB la nong o ban au cua A, B tham gia phan ng

2.Phan ng n gian va phan ng phc tap

Nhng phan ng ch xay ra qua mot giai oan c goi la phan ng ngian.

V du:

NO + O3 = NO2 + O2

Con nhng phan ng xay ra qua nhieu giai oan c goi la phan ng phctap.

V du:

Phan ng: 2N2O5 = 4NO2 + O2 thuoc loai phan ng phc tap v no xayra qua hai giai oan:

N2O5 = N2O3 + O2 (cham)

N2O5 + N2O3 = 4NO2

Moi giai oan cua phan ng hoa hoc nh vay c goi la mot tac dung ngian, tap hp chung ta cc che phan ng.



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3.Phan t so va bac phan ng

Phan t sola so phan t tham gia vao mot tac dung n gian.

Bac phan ng la tong so so mu cua nong o cac chat phan ng trong bieu

thc cua nh luat tac dung khoi lng.oi vi cac phan ng n gian th phan t so va bac phan ng trung nhau.

Nhng oi vi phan ng phc tap th oi khi bac phan ng va phan t so khongtrunh nhau.

V du, trong phan ng tren bac phan ng la 2 nhng phan t so la 1 (giaioan cham nhat).

Trong trng hp nong o cac chat phan ng rat khac nhau cung vay, vdu, phan ng thuy phan ng:

C12H22O11 (r) + H2O (l) = 2C6H12O6 (dd)

La phan ng bac mot v lng nc dung rat d khong anh hng en quatrnh phan ng.

4.Nang lng hoat hoa

Nang lng hoat hoa cua chat phan ng la nang lng d can thiet (so vinang lng trung bnh) cua cac tieu phan e phan ng co the xay ra.

Nang lng hoat hoa cua phan ng la tong nang lng hoat hoa cua cac chattham gia phan ng (vi he so ty lng tng ng). T o thay rang, phan ng conang lng hoat hoa cang nho th phan ng cang nhanh.

II. C CHE PHAN NG THE PHOI T

Theo Ingold, co the chia cac phan ng the thanh hai loai: phan ng the ainhan (SN) va phan ng the ai electron (SE) tuy thuoc vao nhom c a vao chohoac nhan electron. Cac tac nhan ai nhan nhng cac cap electron cua mnh chocac tac nhan ai electron (nguyen t trung tam).

Thong thng th s the mot phoi t nay bang mot phoi t khac c goi la

s the ai nhan, con s the mot nguyen t trung tam nay bang mot nguyen t trungtam khac c goi la s the ai electron. Trong hoa hoc phc chat thng gap phanng the ai nhan va chung ta ch xet c che phan ng the kieu nay.

Co the phan biet ve c ban hai kieu c che the ai nhan trong hoa hoc phcchat nh sau:

C che SN1: au tien phc chat phan ly mot phoi t, dau o phoi t michiem v tr ma phoi t cu a phan ly.



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S o c che SN1 c bieu dien v du nh sau:

- X- + Y-

[L5MX]n+ => [L5M](n+1)+ => [L5MY]n+

Cham Nhanh

ac iem cua phan ng kieu nay la giai oan au (mat X-) tien hanh chamva do o, no quyet nh toc o cua toan bo phan ng. Sau o phc chat trung gianco so phoi tr nho hn co the ket hp hau nh tc thi vi phoi t mi (Y-).

Neu c che tren la ung th ta co:

v = kC[L5MX]n+

Bieu dien SN1 co ngha la s the ai nhan n phan t.

C che SN2: Trong trng hp nay khong xay ra s phan ly ma ngc lai,phoi t the va phoi t b the cung ton tai mot thi gian nao o dang phc chathoat ong. Khi o di anh hng cua phoi t the, phoi t b the dch chuyen khoiv tr can bang roi t ra nhng cho cho phoi t the. Nh vay phc chat hoat ongtrong trng hp nay co so phoi tr ln hn cua phc chat au mot n v.

S o c che SN2 c bieu dien v du nh sau:

+ Y- X - X-

[L5MX]n+ => [L5M ](n-1)+ => [L5MY]n+

Cham Y NhanhNeu c che tren la ung th toc o phan ng se ty le vi tch so cac nong o

cua hai chat:

v = kC[L5MX]n+CY-

Bieu dien SN2 co ngha la s the ai nhan nh (hay lng) phan t.

Nh vay, hai kieu c che tren, trang thai au va cuoi cua he nh nhau, chkhac nhau trang thai trung gian.

Hai c che the va trnh bay tren la hai trng hp gii han, con c chethc thng t khi n gian nh vay. V vay, chung ta dung nhng ky hieu SN1 VaSN2 khong phai e ch nhng trng hp gii han ma e ch nhng c che gan vitrng hp gii han o. S d co s phc tap nh vay la v, khi da theo nh luattac dung khoi lng th ngay ca gan ung cung khong the biet c phan ng tienhanh theo c che SN1 hay SN2. Co the thay ro ieu nay qua hai v du sau ay:

1. Tng tac vi dung moi

a so phan ng cua phc chat tien hanh trong dung moi la nc. V vay

nc co the tham gia vao cac giai oan cua phan ng the. V du co the xay ra cacphan ng sau:



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[L5MX] + H2O => [L5MH2O] + X (cham)

[L5MH2O] + Y => [L5MY] + H2O (nhanh)

hoac:

- X + Y[L5MX] => [L5M] => [L5MY]n+

Cham Nhanh

Hai qua trnh nay eu c ac trng bang cung mot bieu thc cua nh luattac dung khoi lng, ngha la:

v = kC[L5MX]n+

Nh vay neu ch da vao bieu thc tnh toc o phan ng v th khong the biet

phan ng xay ra theo c che nao.2. S tao thanh cap ion:

Neu phc chat phan ng la cation con nhom the i vao la anion va ac bietneu mot hoac ca hai co ien tch ln th mot chng mc nao o co the tao thanhcap ion (con goi la phc chat ngoai cau):

[L5MX]n+ + Ym- => [L5MX]Yn-m

Neu ch da vao bieu thc:

v = kC[L5MX]n+

CYm-

Th khong the biet c phan ng tien hanh theo c che SN2 hay theo kieutao thanh cap ion. Ngay ca neu biet c co s tao thanh cap ion th cung khongthe biet c cap ion o bien thanh phc chat mi nh the nao.

III. PHAN NG THE TRONG PHC CHAT BAT DIEN

1. S the cac phoi t nc trong phc chat aqu

Trc het xet qua trnh trao oi cac phan t nc trong cau noi phc chat vi

cac phan t nc dung moi.[M(H2O)6]n+ + 6H2O* = [M(H2O*)6]n+ + 6H2O

(Trong o O* la ong v O18)

Hau het cac phan ng kieu nay tien hanh rat nhanh, v vay toc o phan ngc nghien cu chu yeu bang phng phap tch thoat. Noi dung cua phng phapnay la s pha huy can bang cua he, chang han bang cach thay oi nhiet o. ieukien mi o (co nhiet o cao hn), he khong con trang thai can bang na. Sauo ngi ta o toc o thiet lap can bang. Neu co the o c nhiet o dung dch

trong khoang 10-8

giay th co the o c toc o phan ng, oi hoi phai khoangthi gian ln hn 10-8 giay.



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Bang 4- Chu ky ban trao oi 250C (s) [D kien cua M. Eigen]

Li Na K Rb Cs

Be Mg Ca Sr Ba

Sc Y La

Al Ga In Tl Zn Cd Hg

NiCo

Mn Cu

1 10-2 10-4 10-6 10-8 10-10

oi vi cac ion kim loai kiem va kiem tho: kch thc va ien tch cuachung co anh hng en toc o trao oi nc. Trong moi phan nhom, toc o phanng tang khi kch thc ion tang, con oi vi cac ion M+ va M2+ gan nhau ve kchthc th ion co ien tch be (M+) s trao oi xay ra nhanh hn nhieu. Lien ketM-OH2 co o ben tang khi tang ien tch va giam kch thc cua ion kim loai: cacion co kch thc be va ien tch ln tao phc chat ben hn. T o ta thay, toc ophan ng trao oi phu thuoc vao o ben lien ket M-OH2: lien ket cang ben, toc otrao oi cang cham. Moi lien quan o chng to rang, trong cac phan ng nay,trang thai trung gian at c bang cach t lien ket M-OH2 thng xay ra hn sovi cach hnh thanh lien ket mi (cha t lien ket cu), co ngha la theo c che

SN1.Cung tng t nh vay oi vi cac ion kim loai nhom III (chnh va phu).

oi vi cac ion kim loai chuyen tiep day th nhat M2+ th phc chat aqucua chung co toc o trao oi khong theo trat t ve kch thc cua ion kim loai tdo. Trong o, phc chat cua Ni2+ phan ng cham nhat con phc chat cua Cu2+ phanng nhanh nhat. ieu nay c giai thch bang thuyet trng tinh the. Chu y laphc chat aqu cua chung la phc chat spin cao.

Phan ng trao oi cua chung van theo c che SN1, ngha la phc chat trung

gian hoat ong cua chung co so phoi tr 5 dang thap vuong. So sanh nang lng onnh bi trng tinh the cua phc chat bat dien va phc chat hoat ong cua nothay rang: Neu nang lng on nh bi trng tinh the cua phc chat au ln hnso vi nang lng on nh cua phc chat hoat ong th phc chat au se phan ngcham va ngc lai. S d nh vay la v, bien thien nang lng on nh c avao nang lng hoat hoa cua qua trnh. Neu phc chat hoat ong co nang lng onnh nho hn so vi phc chat au th se lam tang nang lng hoat hoa cua phanng, do o, lam giam toc o phan ng cua no.

T bang thay rang, hau het cac phc chat bat dien khi phan ng th tao thanhphc chat trung gian hoat ong co so phoi tr 5 dang thap vuong vi c che SN1.Khi chuyen t phc chat bat dien sang phc chat thap vuong, cac he d1, d6;d2, d7co bien thien nang lng am, ngha la nang lng hoat hoa E* cua phan ng giam



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xuong, do o toc o phan ng phai ln, ac biet he d4, d9 lai cang phan ng nhanhhn. Con oi vi he d3, d8 co bien thien nang lng dng nen phan ng dien racham.

Bang 5- Nang lng on nh bi trng tinh the () cua phc chat bat dien

va phc chat hoat ong dang thap vuong cua cac he ion d khac nhau

Nang lng on nh bi trng tinh the ()He

Phc chat bat dien Phc chat thapvuong

Bien thiennang lng

d0

d1,d6

d2,d7

d3,d8

d4,d9

d5,d10

0

0,40

0,80

1,20

0.60

0

0

0,45

0,90

1,00

0,90

0

0

-0,05

-0,10

+0,20

-0,30

0

Rieng oi vi phc chat [Cu(H2O)6]2+ v co hieu ng Jahn-Teller nen haiphoi t H2O hai lien ket dai se c trao oi nhanh nhat.

Ngoai viec xet s trao oi cac phan t nc noi cau va phan t nc dungmoi ra, ngi ta con xet s trao oi cac phan t nc noi cau vi cac phoi t khacnh SO42-, S2O32-, va cung thay rang, toc o cua phan ng:

[M(H2O)6]n+ + L2- => [M(H2O)5L]n-2 + H2O

Ch phu thuoc nong o cua cac ion hydrat hoa ma khong phu thuoc nong ocua phoi t i vao.

v = kC[M(H2O)6]n+

Ngha la, phan ng xay ra theo c che SN1.

2.Phan ng the cac phoi t trong cau noi

Phng trnh chung cua cac phan ng the cac phoi t trong cau noi cua phcchat bat dien co the viet di dang:

[L5MX] + Y = [L5MY] + X



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V du:

[Co(NH3)5Cl]2+ + H2O = [Co(NH3)5OH2]3+ + Cl-

Noi chung, cac phan t amoniac va ammin b the rat cham bi cac phoi t

nc nen ngi ta thng xet s the cac goc axit X-

, ch khong xet s the cac phoit ammin.

Phan ng tren la phan ng bac nhat v trong dung dch nc nong o cuanc luon luon bang khoang 55,5 M/l nen khong the xac nh c anh hng cuabien thien nong o nc en toc o phan ng. Do o cac phng trnh toc o:

v = kC[Co(NH3)5Cl]2+

v = kC[Co(NH3)5Cl]2+CH2O

khong phan biet c bang thc nghiem, v k = k'CH2O = k'55,5.

Neu da vao phng trnh toc o phan ng th khong the biet c nc cotham gia vao giai oan quyet nh toc o cua phan ng hay khong. Muon bietphan ng tien hanh theo c che nao can phai s dung cac d kien thc nghiemkhac.

a- So sanh toc o cua hai phan ng thuy phan axit sau:

[Co(NH3)4Cl2]+ + H2O = [Co(NH3)4OH2Cl]+ + Cl-

[Co(NH3)5Cl]2+ + H2O = [Co(NH3)5OH2]

3+ + Cl-

thay rang, toc o cua phan ng au ln hn khoang 1000 lan toc o cua phan ngsau. S d nh vay la v do s tang ien tch cua ion phc chat a lam cho o benlien ket Co-Cl tang len va v vay lien ket cang kho t hn. T s lien quan giatoc o phan ng va o ben cua lien ket (toc o phan ng tang khi o ben lien ketgiam va ngc lai) co the noi rang trong trng hp nay c che phan ly SN1 co xacsuat ln hn.

b- So sanh toc o cua cac phan ng thuy phan cua mot day phc chat tng ttrans-[CoEn2Cl2]+.

Trong cac phc chat nay, phan t etylendiamin c thay the bang cacammin tng t, trong o cac nguyen t hydro nguyen t cacbon c thay thebang nhom CH3. Cac phc chat nay phan ng nhanh hn phc chat cua En.

Bang 6- Toc o phan ng the cac phc chat diammin tng t bi phoi tnc pH = 1, t0 = 250C

Cong thc diammin k.104(s-1)

H2N-CH2-CH2-NH2

H2N-CH2-CH(CH3)-NH2

H2N-C(CH3)2-C(CH3)2-NH2

0,3

0,6

tc thi



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S the cac nguyen t H bang cac nhom CH3 lam tang the tch cua phoi t, doo a gay kho khan cho phoi t khac en gan ion kim loai. Chng ngai khonggian o se lam cham phan ng theo c che SN2. S co mat cac phoi t cong kenh gan ion kim loai se tao ieu kien cho qua trnh phan ly. Viec tang toc o phanng thuy phan cua cac phc chat co phoi t cong kenh chng to phan ng tienhanh theo c che SN1.

Xet phan ng the kieu:

[Co(NH3)5X]2+ + Y- = [Co(NH3)5Y]

2+ + X-

trong o Y- la cac goc axit ma khong phai la nc, xay ra qua giai oan aula the X- bang nc, roi sau o phoi t H2O mi c thay the bang Y-:

[Co(NH3)5X]2+ + H2O = [Co(NH3)5OH2]3+ + X- (cham)

[Co(NH3)5OH2]

3+

+ Y

-

= [Co(NH3)5Y]

2+

+ H2O (nhanh)Nh vay, trong phan ng tren, toc o cua chung bang toc o cua giai oan

thuy phan (giai oan cham).

Ch co ion OH- la khac vi tat ca cac tac nhan khac ve kha nang phan ngvi cac ammin cua Co3+. Phan ng tien hanh rat nhanh (106 lan hn nc) theokieu thuy phan baz:

[Co(NH3)5Cl]2+ + OH- = [Co(NH3)5OH]2+ + Cl-

v = kC[Co(NH3)5Cl]2+COH-

Theo Ingold, Newholm, th da vao cho phan ng tien hanh nhanh va bacphan ng tong cong la 2 nen gia thiet rang OH- la tac nhan ai nhan co hieu lc acbiet oi vi cac phc chat cua Co3+ va phan ng tien hanh theo c che SN2.

Theo Basolo, Pearson th cac phan ng nay tien hanh theo c che qua canbang axit-baz:

[Co(NH3)5Cl]2+ + OH- = [Co(NH3)4NH2Cl]+ + H2O (nhanh)

[Co(NH3)4NH2Cl]+ = [Co(NH3)4NH2]2+ + Cl- (cham)

[Co(NH3)4NH2]2+ + H2O = [Co(NH3)5OH2]2+ (nhanh)

Trong giai oan au phc chat [Co(NH3)5Cl]2+ la axit, con[Co(NH3)4NH2Cl]+ la baz lien hp cua no (theo thuyet axit-baz cua Bronsted vaLaury). Sau o phan ng tien hanh theo c che SN1. C che nay cung phu hp vibac phan ng tong cong la 2, v giai oan quyet nh toc o phan ng bao gombaz lien hp vi phc chat au-axit cho nen c che nay la SN1-CB. Theo Basolo,c che nay ch ap dung cho cac hp chat cha proton linh ong. Rat kho xac nhc rang, trong hai c che tren th c che nao giai thch tot cac d kien thc

nghiem. Tuy vay, co nhieu bang chng e xac nhan c che SN1-CB hn la c cheSN2:



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+ Noi chung, cac phc chat cua Co3+ phan ng theo c che SN1 va khong co lydo g e noi rang, ion OH- gay ra qua trnh the kieu SN2.

+ Cac phc chat cua Co3+ tham gia phan ng trong dung moi khong phai lanc cung tao thanh phc chat hoat ong co so phoi tr 5. ieu nay cung chng to

c che phan ng la SN1.

+ Mat khac thay rang, khi trong phc chat cua Co3+ khong co cac lien ket N-H(khong co cac nhom ammin) th phc chat nay phan ng rat cham vi OH -. ieunay cho phep ket luan rang, oi vi toc o phan ng th tnh chat axit-baz cuaphc chat quan trong hn tnh chat ai nhan cua OH-.

Hien nay ngi ta a nghien cu nhieu phan ng the cua mot so ln cacphc chat bat dien va a so la theo c che SN1. S d nh vay la v, 6 phoi t phoitr ay u xung quanh ion trung tam nen ch con t cho e co the ket hp them cac

nhom khac. Tuy vay, cung co mot so t trng hp theo c che SN2 vi phc chathoat ong co so phoi tr bang 7.

IV. PHAN NG THE TRONG PHC CHAT VUONG PHANG

oi vi cac phc chat vuong phang, c che phan ng cua chung n gianhn. Chung co khuynh hng thc hien c che SN2 nhieu hn la cac phc chat batdien.

Nghien cu cac phan ng the cua cac phc chat Pt2+:

oi vi phan ng kieu sau ay trong dung dch nc:

[PtLnCl4-n]n-2 + Y = [PtLnCl3-nY]n-1 + Cl-

Phng trnh toc o co dang chung la:

v = kC[PtLnCl4-n]n-2 + k'C[PtLnCl4-n]n-2CY

So hang th hai cua phng trnh ng vi phan ng theo c che SN2 thccua Y vi phc chat, con so hang au bieu dien qua trnh gom hai giai oan: giaioan au, mot ion Cl- c thay the bang mot phan t nc (co le cung theo cche SN2) quyet nh toc o chung cua qua trnh, giai oan sau s the H2O bang Y

xay ra nhanh.Ngi ta thay rang, toc o cua phan ng tren trong day bon phc chat vi L

= NH3, Y = H2O va n = 0=>3 ch thay oi 2 lan. Trong day nay, ien tch cua ionphc thay oi t -2 en +1. Khi tang ien tch dng cua phc chat th lien ket Pt-Cl cang kho t trong khi o, s tao thanh lien ket gia Pt va nhom the mi (H2O)cang thuan li. Nhng toc o phan ng th hau nh khong oi (thay oi rat t).ieu o chng to c che phan ng phai la SN2, trong o s t lien ket Pt-Cl cungnh s tao thanh lien ket Pt-OH2 eu quan trong nh nhau.

Chung ta xet cu the phan ng tien hanh trong dung dch nc sau ay:

[Pt(NH3)3Cl]+ + Br- = [Pt(NH3)3Br]+ + Cl-



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V. HIEU NG ANH HNG TRANS

1.Hieu ng:

Khi nghien cu phan ng the phoi t trong cac phc chat vuong phang cuaPt2+, vien s I. I. Secnhiaep a tm ra hieu ng anh hng trans nh sau: Toc o cuaphan ng the mot phoi t nao o c quyet nh chu yeu bi ban chat cua phoi tnam v tr trans oi vi no. Neu phoi t L cang hoat ong ve mat anh hngtrans th phoi t nam v tr trans oi vi no cang linh ong va toc o the phoi to cang ln.

Khi tnh en anh hng trans th trong phc chat :

B

L - M - A

B

Kha nang the phoi t A c quyet nh chu yeu bi ban chat cua L, con Bch ong vai tro phu.

au tien quy luat nay c nghien cu va thiet lap oi vi mot so ln phc

chat vuong phang cua Pt2+

.oi vi phc chat vuong phang cua Pt2+ day giam o hoat ong trans cua cac

phoi t nh sau:

CN-, C2H4, CO > R3P > SC(NH2)2 > NO2-, SCN- > I- . Br- > Cl- > F- > NH3,En/2 > Py, RNH2 > OH- > H2O

Khi chuyen t kim loai tao phc nay sang kim loai tao phc khac th oi vicac phoi t mot nguyen t (F-, Cl-,) day nay khong thay oi nhng ai lngtuyet oi co thay oi, con oi vi cac phoi t nhieu nguyen t th co s thay oi

rat ln ve v tr va o anh hng.V du, NO2- trong cac phc chat cua Pt2+ va Co3+ co o anh hng trans ln,

trong khi o phc chat cua Pt4+ o anh hng cua no lai nho. Cu the la:

I- > Br- > Cl- > OH- > NH3 >NO2- > Py

Day o hoat ong trans tren rat co ch cho viec hoan thien nhng phngphap tong hp a biet va tm ra cac phng phap tong hp mi cung nh giai thchtnh chat cua cac ong phan hnh hoc.



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V du, s o tong hp muoi Payron (ong phan cis):

Cl 2- +NH3 NH3 - +NH3 NH3

Cl-Pt-Cl ====> Cl-Pt-Cl ====> Cl-Pt-NH3

Cl -Cl-

Cl -Cl-

Cl

Con muoi Rayze (ong phan trans) c tong hp theo s o:

NH3 2+ +Cl- NH3 + +Cl

- NH3

H3N-Pt-NH3 ====> Cl-Pt-NH3 ====> Cl-Pt-Cl

NH3 -NH3 NH3 -NH3 NH3

2. Giai thch hieu ng anh hng trans:

Theo Grinbe va Nhecraxop: Da tren hieu ng phan cc

Trong day o hoat ong trans, cac phoi t c sap xep hau nh cung tht vi day ve cng o ai nhan cua cac phoi t the. ieu o chng to rang, trongca hai day, o phan cc ong vai tro quan trong. Tuy vay rat kho giai thch anhhng cua o phan cc en s lam yeu lien ket cua phoi t v tr trans. Co thechng minh n gian la: Trong phc chat MX3L, neu phoi t L co o phan cc lnhn X th s phan bo cac ien tch cam ng se nh sau:

X

L _ M X

X

Do o, phoi t X nam v tr trans oi vi L se b ay manh hn, ngha lalien ket M-X se tr nen yeu hn nen X de b the bi cac phoi t khac

Theo Ia. K. Xrkin: Da tren s lai hoa

Trongphc chat cua Pt2+, ion Pt2+ co s lai hoa dsp2. Cac orbital lai hoa nayxen phu vi cac orbital cua phoi t tao cac lien ket cong hoa tr.

Gia strong phc chat PtX3L, lien ket Pt-L co tnh cong hoa tr hn lien ketPt-X. Khi o, do s lai hoa ma lien ket cong hoa tr se loi keo cac phoi t X nam v tr cis oi vi L (di mot goc 900) vao lien ket cong hoa tr va nh vay phoi tnam v tr trans oi vi L se co tnh chat cong hoa tr kem nhat.



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X CHT manh

L XCHT rat manh CHT yeu

CHT manh

X

Theo Cardwell, Chatt va Orgel: Thc chat cua hieu ng anh hng transkhong phai la cho lam yeu lien ket cua nhom nam oi dien vi phoi t hoat ongtrans ma cho lam giam nang lng hoat hoa khi tao thanh phc chat trung gian

co so phoi tr 5. S o phan ng the lng phan t co the bieu dien nh sau:

X

X X X Y

L Y

L X X L X

X

Khi nhom L en gan phc chat th mot nhom X se chuyen dch xuong dimat phang vuong ban au. Nhom X b dch chuyen, nhom X v tr trans oi vino va nhom L i vao se tao thanh mat phang trung tam cua hnh lng chop tamgiac. Sau o mot trong hai nhom X mat phang tam giac se nhanh chong b matva cau hnh vuong phang c khoi phuc.

Theo Chatt va Orgel, neu trong phc chat vuong phang ma phoi t co

khuynh hng keo nhng electron ban eu a c ien cac orbital dxz va dyzcua nguyen t kim loai th mat o electron tren va di lien ket tao thanh giaion kim loai va phoi t nam v tr trans oi vi no se giam i lam cho vungkhong gian o tr nen thoang hn, tao ieu kien cho phoi t ben ngoai tan congvao.

oi vi phc chat vuong phang cua platin th cac cap electron cac orbital dcua no se tng tac vi cac orbital * cua phoi t (neu phoi t la nhng nhomcha bao hoa, v du: C2H4, CO, NO) va tng tac vi cac orbital d con trong cuaphoi t (neu phoi t la cac nhom nh R2S, R3P,). Do o, gia phoi t L va ion

trung tam tao lien ket kieu cho (M=>L) ngoai lien ket cho-nhan (L=>M).



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Trong trng hp chung, thay rang s on nh cua phc chat hoat ong viso phoi tr 5 la do phoi t L keo electron ve pha mnh t orbital d. Orbital d co haiphan hng tng oi trc tiep en phoi t i vao Y va phoi t i ra X'. Khi mato electron b keo dai ra t pha orbital d th cac lien ket vi hai phoi t X' va Y setr nen ben hn v hieu ng ay gia cac orbital d va cac phoi t o giam i. Nhvay o ben cua phc chat hoat ong tang len, nang lng hoat hoa se giam i.Cac hieu ng tng t se khong co neu Y en gan va the mot trong hai phoi t Xnam v tr cis oi vi L.

Mat yeu cua nhng giai thch nay la ch ap dung cho cac phc chat co sophoi tr 4 va ch e cap en mat ong hoc cua hieu ng anh hng trans ch khonggiai thch hien tng tren quan iem nhiet ong hoc. S o tren khong e cap ennhng phoi t nh NH3, OH- hoac H2O v chung khong co orbital *, cung khongco cac orbital d.

Theo Chatt cung nh Basolo va Pearson th co the giai thch anh hng transcua nhng phoi t khong co kha nang tao lien ket t quan iem phan cc.

Tom lai hien nay cha co mot ly thuyet nh lng ve anh hng trans.Nhng cach giai thch tren eu co nhng u iem va nhc iem nhat nh vacha bao quat c toan bo cac d kien thc nghiem.



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Chng VI. TAI LIEU THAM KHAO

1- Le Ch Kien, Giao trnh Hoa hoc phc chat , tap I, II, Trng ai hoc Tong hpHa Noi, 1971

2- ao nh Thc, Cau tao nguyen t va lien ket hoa hoc, tap I, II, Nha xuat banai hoc va THCN, 1975

3- Makasep, Hp chat trong dau moc vuong, Nha xuat ban Khoa hoc va KT, 19804- Glikina, Hoa hoc phc chat , Nha xuat ban Giao duc, 1981



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MUC LUC

Chng I. M AU......................................................................................................2

I. KHAI NIEM PHC CHAT......................................................................................2

II. PHAN LOAI PHC CHAT .................................................................................... 21. Phan loai theo tnh chat gan nhau: ...................................................................... 22. Phan loai theo ien tch: ...................................................................................... 2

III. S LC VE VAI TRO, Y NGHA CUA HOA HOC PHC CHAT:................... 2

Chng II. THUYET CAU TAO PHC CHAT........................................................4

I. CAC THUYET CU .................................................................................................. 4

1. Thuyet amoni (Graham):...................................................................................... 42. Thuyet mach (Blomstred, Iogensen) ................................................................... 5

II. THUYET PHOI TR (VECNE 1893)......................................................................61. S phoi tr: ............................................................................................................ 62. So phoi tr (spt) cua ion trung tam: ...................................................................... 63. Dung lng phoi tr (dlpt) cua phoi t: ................................................................ 64. Danh phap phc chat: theo IUPAC 1960: ........................................................... 75. ong phan cua phc chat:.................................................................................... 7

Chng III. BAN CHAT LIEN KET TRONG PHC CHAT ................................. 8 I. CAC THUYET CU .................................................................................................. 8

1. Thuyet tnh ien COXEN (KOSSEL).................................................................. 82. S phan cc Ion va Phan t: .............................................................................. 103. Thuyet lien ket cong hoa tr LIUYT (LEWIS).................................................. 11

II. CAC THUYET LNG T.................................................................................121. Thuyet lien ket hoa tr (LH hay VB- valence bond)......................................... 122. Thuyet trng tinh the........................................................................................ 163. Thuyet ORBITAL Phan t (OP hay MO- molecular orbital) ........................... 27

Chng IV. CAC PHNG PHAP NGHIEN CU PHC CHAT....................... 30

I. PHNG PHAP TONG HP N

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