Inorganic Chemistry 2 - Yazd · Inorganic Chemistry 2 An introduction to Coordination Chemistry...

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Inorganic Chemistry 2

An introduction to

Coordination Chemistry

Alireza Gorjiagorji@yazd.ac.ir

Department of Chemistry, Yazd University

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Coordination Chemistry

Alfred Werner1866-1919

Nobel prize 1913

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Transition Metals فلزات واسطه

20_432

Sc

Y

La*

Ac†

Ti

Zr

Hf

Unq

V

Nb

Ta

Unp

Cr

Mo

W

Unh

Mn

Tc

Re

Fe

Ru

Os

Co

Rh

Ir

Ni

Pd

Pt

Cu

Ag

Au

Zn

Cd

Hg

Ce

Th

Pr

Pa

Nd

U

Pm

Np

Sm

Pu

Eu

Am

Gd

Cm

Tb

Bk

Dy

Cf

Ho

Es

Er

Fm

Tm

Md

Yb

No

Lu

Lr

d-block transition elements

*Lanthanides

†Actinides

f-block t ransition elemen ts

Uns Uno Une Uun Uuu

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A neutral molecule or ion having a lone electron

pair (Lewis base B) that can be used to form a

bond to a metal ion (Lewis acid A).

Coordination compounds

Complexes

A + :B A-BA Metal atom or Metal ion

B Ligand (nutral molecule or ion)

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A complex consists of a central atom, which is

usually a metal atom or ion, and attached groups

called ligands

Terminology for Complexes

The coordination

number is the total

number of points at

which a central atom

or ion attaches

ligands

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Terminology for Complexes

The region surrounding the central atom or ion and

containing the ligands is called the coordination sphere

A substance

consisting of one or

more complexes is

called a

coordination

compound

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Terminology for Complexes

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Terminology for Complexes

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Constitution and Isomerism ساختار و ایزومری

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Linear Complexesagorji@yazd.ac.ir

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Tetrahedral Complexesagorji@yazd.ac.ir

18Square Planar Complexes

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Coordination Number: 5

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N

NH NH

N

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Myoglobin, a protein that stores O2 in cells

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Coordination Environment of Fe2+ in Oxymyoglobin and

Oxyhemoglobin

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Trigonal-Prismatic Complexes

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Distortion from Octahedral Geometry

Tetragonal distortion

Rhombic

distortion

Trigonal

distortion

Elongation

Compression

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– Ligands

• Ligands are often organic molecules with IUPAC names

• Common names are most often used for the ligands in coordination compounds

• Chelate = Greek for Claw = a ligand that can bind a metal ion by more than one point of attachment. – Bidentate = “two teeth” = NH2CH2CH2NH2 = ethylenediamene = en

– Tridentate = NH2CH2CH2NHCH2CH2NH2 = diethylenetriamine = trien

– Tetradentate = cyclam

• lists common ligands, names, structures, and abbreviations

Nomenclature of Coordination Complexes

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Polydentate refers to multiple points of attachment by one ligand

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Transition

Metal

Name if in Cationic

Complex

Name if in Anionic

Complex

Sc scandium scandate

Ti titanium titanate

V vanadium vanadate

Cr chromium chromate

Mn manganese manganate

Fe iron ferrate

Co cobalt cobaltate

Ni nickel nickelate

Cu copper cuprate

Zn zinc zincate

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1. The cation comes first, then the anion(s)– diamminesilver(I) chloride [Ag(NH3)2]Cl

– potassium hexacyanoferrate(III) K3[Fe(CN)6]

2. Inner Sphere Complex Ion is enclosed in brackets– Ligands are named before the metal

– Metal is written first in the formula

– A space only between cation and anion

– No capitalization is needed

» tetraamminecopper(II) sulfate [Cu(NH3)4]SO4

» hexaamminecobalt(III) chloride [Co(NH3)6]Cl3

3. Prefixes denote the number of each ligand type. Special prefixes and parentheses are used if the ligand already contains a prefix.2 di bis 6 hexa hexakis

3 Tri tris 7 hepta heptakis

4 tetra tetrakis 8 octa octakis

5 penta pentakis 9 nona nonakis

10 deca decakis

Nomenclature of Coordination Complexes

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– dichlorobis(ethylenediamine)cobalt(III) fluoride [Co(en)2Cl2]F

– tris(bipyridine)iron(II) chloride [Fe(bipy)3]Cl2

4)Ligands are named in alphabetical order not counting prefixes.– tetraamminedichlorocobalt(III) ion [Co(NH3)4Cl2]

+

– amminebromochloromethylamineplatinum(II) [Pt(NH3)BrCl(CH3NH2)]

5)Ligand name alterations:– Anionic ligands are given an -o suffix: chloro, flouro, oxo, sulfato

- Neutral ligands keep their name: methylamine, bipyridine

– Water becomes aqua

– NH3 becomes ammine to keep separate from alkylamines

6)Two systems for showing charge or oxidation state of metal ion– Stock system: oxidation state in Roman Numerals in parenthesis after the metal

ion name. This is the most common method.

– Ewing-Basset system: charge of the total complex ion is placed in parenthesis

after the name of the metal ion.

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Both systems add –ate to the metal name if the complex ion has an overall (-) charge

[Pt(NH3)4]2+ = tetraammineplatinum(II) ion or (2+)

[PtCl4]2- = tetrachloroplatinate(II) ion or (2-)

[PtCl6]2- = hexachloroplatinate(IV) ion or (2-)

7)Isomer designations come before the rest of the name and in italics

– cis-diamminedichloroplatinum(II)

– trans-diamminedichloroplatinum(II)

8) Bridging ligands have the prefix m

[(NH3)4Co(OH)(NH2)Co(NH3)4]4+ =

-amido--hydroxobis(tetraamminecobalt(III)) ion

9)Negatively charged complexes of certain metals use their Latin names:

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K2[Co(NH3)2Cl4]

potassium diamminetetrachlorocobaltate(II)

[Co(NH3)4Cl2]Cl

tetraamminedichlorocobalt(III) chloride

[Co(NH3)4Cl2]+

tetraamminedichlorocobalt(III) ion

[Ru(NH3)4(HSO3)2]tetraaminebis(bisulfito)ruthenium(II)

[Ti(H2O)6][CoCl6]hexaaquatitanium(III)hexachlorocobaltate(III)

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K3[Fe(CN)6]

potassium hexacyanoferrate(III)

[Fe(CN)6]3-

hexacyanoferrate(III) ion

[Co(NH3)6]3+

[Fe(SCN)6]3-

[Co(en)3]3+

[Cr(C2O4)3]3-

[Fe(NH3)4(o-phen)]3+

[Fe(EDTA)]-1

[Co(EDTA)]-1

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20_441

Isomers

(same formula but different properties)

Stereoisomers

(same bonds, different

spatial arrangements)

Structural

isomers

(different bonds)

Optical

isomerism

Geometric

(cis-trans)

isomerism

Linkage

isomerism

Coordination

isomerism

Isomerism ایزومری

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Coordination Isomerism ایزومری کوئوردیناسیون

[Co(NH3)6][Cr(CN)6]

hexaaminecobalt(III) hexacyanochromate(III)

[Cr(NH3)6][Co(CN)6]hexaaminechromium(III) hexacyanocobaltate(III)

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Ionization Isomerism ایزومری یونش

[CrSO4(NH3)5]Cl

[CrCl(NH3)5]SO4

pentaaminsulfatochromium(III) chloride

pentaaminchlorochromium(III) sulfate

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Hydrated Isomerism ایزومری آب پوشی

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[Co(NH3)4(NO2)Cl]Cl & [Co(NH3)4(ONO)Cl]Cl

[Co(SCN)(NH3)5]+ & [Co(NCS)(NH3)5]

+

Ambidentate Ligands لیگاندهای دوسردندانه

NCS- NO2- R-CONH2

Linkage Isomerism ایزومری اتصال

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[Co(NH3)5(NO2)]Cl2Pentaamminenitrocobalt(III) chloride

[Co(NH3)5(ONO)]Cl2Pentaamminenitritocobalt(III) chloride

Linkage Isomerism ایزومری اتصال

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20_441

Isomers

(same formula but different properties)

Stereoisomers

(same bonds, different

spatial arrangements)

Structural

isomers

(different bonds)

Optical

isomerism

Geometric

(cis-trans)

isomerism

Linkage

isomerism

Coordination

isomerism

Isomerism ایزومری

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Stereoisomerism استریوایزومری

1- Geometric isomerism

1. Geometric isomerism (cis-trans):

Pt(NH3)2Cl2

2. Geometric isomerism (fac-mer):

IrH3(PR3)3

– Atoms or groups arranged differently spatially relative to metal ion

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Geometric Isomerism ایزومری هندسی

cis-trans ترانس–سیس

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ML3X3•fac (facial) وجهی

three identical ligands occupying the

corners of a common triangular

•mer (meridional) کمربندی

three identical ligands occupying three

consecutive corners of a square plane

Geometric Isomerism ایزومری هندسی

fac-mer کمربندی –وجهی

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IrH3(PMe3) 3

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تحمیل ایزومری به وسیله لیگاند

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Each of the two

molecules or ions of

an optical isomer is

called an

enantiomer and each

enantiomer rotates

the plane-polarized

light in opposite

directions

2- StereoisomerismStereoisomerism استریوایزومری

2- Optical isomerism نوری ایزومری

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Sn S1= S2=iCn Dn

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Optical Activity فعالیت نوری

Optical isomers are isomers that differ in their

ability to rotate the plane of polarized light

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• Different all ligands

• Tris bidentate chelate

• cis bis bidentate chelate

• Chiral organic ligand

• …

• …

• …

Chiral Complexes

Sn S1= S2=i

Cn Dn

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Optical Isomerism نوریایزومری

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Optical Isomerism نوریایزومری

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Presentation of [M(en)3]

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EnantiomerDiasteriomer

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Complex-Ion Equilibria

Kf = [[Zn(NH3)4]2+]

[Zn2+][NH3]4 = 4.1*108

Zn2+(aq) + 4 NH3(aq) [Zn(NH3)4]2+(aq)

[Zn(H2O)4]2+(aq) + NH3(aq) [Zn(H2O)3(NH3)]2+(aq) + H2O(aq)

K1= [[Zn(H2O)3(NH3)]2+]

[[Zn(H2O)4]2+][NH3]= 1 = 3.9*102

Displacement is stepwise from the hydrated ion:

Step 1:

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[Zn(H2O)3(NH3)]2+(aq) + NH3(aq) [Zn(H2O)2(NH3)2]2+(aq) + H2O(aq)

K2 = [[Zn(H2O)2(NH3)2]2+]

[[Zn(H2O)3(NH3)]2+][NH3]= 2.1*102

K = 2 =[[Zn(H2O)2(NH3)2]2+]

[[Zn(H2O)4]2+][NH3]2= K1 * K2 = 8.2*104

Step 2:

[Zn(H2O)4]2+(aq) + 2 NH3(aq) [Zn(H2O)2(NH3)2]2+(aq) + 2 H2O(aq)

Combining steps 1 and 2:

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Kn+1اگر > Knستشد نشان دهنده تغییرات ساختاری یا تغییرات اسپینی ا

[Fe(OH2)6]2+ + bipy [Fe(OH2)4 (bipy)]2+ K1

[Fe(OH2)4 (bipy)]2+ + bipy [Fe(OH2)2 (bipy) 2]2+ K2

[Fe(OH2)2 (bipy) 2]2+ + bipy [Fe (bipy) 3]

2+ K3

K3 > K2

eg

t2g

eg

t2g

eg

t2g

K3K2

Kn+1اگر > Knستشد نشان دهنده تغییرات ساختاری یا اسپینی ا

[Cd(OH2)6]2+ + Br-

[Cd(OH2)5 Br] + K1

[Cd(OH2)5 Br] + + Br- [Cd(OH2)4 Br2] K2

[Cd(OH2)4 Br2] + Br- [Cd(OH2)3 Br3]

- K3

[Cd(OH2)3 Br3]- + Br-

[CdBr4]2- K4

logK1=1.56 > logK2=0.54 > logK3=0.06 <logK4=0.37

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Irving Williams Seies

Fig is obtained when log Kf is plotted for comps. of the M2+ ions

of the first series. This variation is summarized by the Irving-

Williams series for the order of formation constants. For M2+:

Ba2+ < Sr2+ < Ca2+ < Mg2+ < Mn2+ < Fe2+ < Co2+ < Ni2+ < Cu2+ > Zn2+

The order is relatively insensitive to the choise of ligands

The series reflects electrostatic effects.

However, beyond Mn2+ there is a sharp

increase in the value of Kf for Fe(II),

d6, Co(II), d7, Ni(II) d8,and Cu(II) d9.

These ions experince an additional

stabilization proportional to the LFSE.

Tetragoanally distorted Cu(II) enhances

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Chelate Effect

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Macrocyclic Ligands

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Acid-Base Reactions of Complex Ions

[Fe(H2O)6]3+(aq) + H2O(aq) [Fe(H2O)5(OH)]2+(aq) + H3O+(aq)

Ka1 = 9*10-4

[Fe(H2O)5(OH)]2+ (aq) + H2O(aq) [Fe(H2O)4(OH)2]2+(aq) + H3O+(aq)

Ka2 = 5*10-4

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