11

Molecular and Gold Nanoparticles Supported N-Heterocyclic Carbene Silver(I) Complexes – Synthesis, Characterization and Cataly

tic Applications

學 生 :王趙增指導老師 : 于淑君 博士

2009 / 04 / 27Department of Chemistry & Biochemistry

Chung Cheng University

22

N-Heterocyclic CarbenesN-Heterocyclic Carbenes

NHCs are strongerσ-donors than the most electron rich phosphine- less likely to dissociate from the metal during the reaction

NHCs have come to replace phosphines in many organometallic and organic reactions

NHCs can be useful spectator ligands, tunable electronically and sterically

NHCs are most frequently prepared via deprotonation of the corresponding azolium salts

33

N-Heterocyclic Carbenes as LigandsN-Heterocyclic Carbenes as Ligands- In the early 90's NHC were found to have bonding properties similar to trialklyphosphanes( -PR3 ) and alkylphosphinates( -OP(OR)R2 ).

- compatible with both high and low oxidation state metals

- examples:

- reaction employing NHC's as ligands:

Herrmann, W. Angew. Chem. Int. Ed. 2002, 41, 1290-1309.

44

The Applications of Ag(I) NHCThe Applications of Ag(I) NHC

Silver(I)-Carbene Complexes as Carbene Transfer AgentsSilver(I)-Carbene Complexes as Carbene Transfer Agents

Addition of arenes to imines

Aza-Diels-Alder reaction

Asymmetric aldol reactionAsymmetric aldol reaction

Barbier-Grignard-type reactionBarbier-Grignard-type reaction

55

The First Silver(I)-Carbene ComplexesThe First Silver(I)-Carbene Complexes

Arduengo.A.J,et.al. Organometallics 1993, 21, 3405-3409

66

Silver(I)-Carbene Complexes as Carbene Silver(I)-Carbene Complexes as Carbene Transfer AgentsTransfer Agents

Wang, H. M. J.; Lin, I. J. B. Organometallics 1998, 17, 972-975

77

MotivationMotivation

Using NHCs ligand to replace phosphine ligand in organUsing NHCs ligand to replace phosphine ligand in organomatallic catalysis.omatallic catalysis.--Immobilization of NHC- Ag(I) complexs onto Au NanoparticlesImmobilization of NHC- Ag(I) complexs onto Au Nanoparticles

Recyclable catalysts and their Applications in solvent-Recyclable catalysts and their Applications in solvent-free system.free system.

Developing a homogeneous catalyst for aldehyde alkyne Developing a homogeneous catalyst for aldehyde alkyne and amine coupling. and amine coupling.

88

ExperimentalExperimentalPreparation of [Ag(hmim)Preparation of [Ag(hmim)22]PF]PF6 6 ComplexComplex

N N

N N

65 oC, 12h95 % yield

[Hmim]Br

Br N N

Br

[Hmim]PF6

PF6KPF6

DI 40oC/1h75 % yield

Ag2O, t-BuOK CH2Cl2 r.t / 4 h

75% Ag

NN

N N

PF6Ag

NN

N N

PF6

99

11H NMR Spectra of [Hmim]HPFH NMR Spectra of [Hmim]HPF66, ,

[Ag(hmim)[Ag(hmim)22]PF]PF66

2H

H 2H

*DMSO

*H2O

*H2O

*DMSO

N N

PF6HH

H

2H

NN

Ag

H H

N N

PF6

HH

1010

1313C NMR Spectra of [Hmim]HPFC NMR Spectra of [Hmim]HPF66, ,

[Ag(hmim)[Ag(hmim)22]PF]PF66

c

N N

HC

PF6

C

Ag

C

C

NN

N N

PF6

*DMSO

*DMSO

1111

Change Temperature Change Temperature 11H NMR Spectra of H NMR Spectra of [Ag(hmim)[Ag(hmim)22]PF]PF66

Temp.:250C Temp.:100C

Ag

NN

N N

PF6Ag

NN

N N

PF6

H H

Ag

NN

N N

PF6

H

H

1212

ESI-MS Spectrum of [Ag(hmim)ESI-MS Spectrum of [Ag(hmim)22]PF]PF66

1313

(A) Addition of (a) HCl, (b) HBr, (c) HBF4, (d) HI,and (e) HPF6. (B) UV-vis absorption spectra corresponding to (a), (d), and (e) in photograph A.

Itoh, H.; Naka, K.; Chujo, Y. J. Am. Chem. Soc. 2004, 126, 3026-3027.

Ionic Liquids As Stabilizing Agents for NPsIonic Liquids As Stabilizing Agents for NPs

NN+

CH2 S

2

+

HAuCl4

6

NaBH4

S

Cl-

NN+

Cl-

Aun

1414

Synthetic StrategySynthetic Strategy

N N +Br

BrDMF / 80oC

12 hNN

Br

Br

1. CS(NH2)2 / ethanol

2. reflux , 16 hr

3. NaOH / 5 min

4. HCl /20 min

NNSH

Br

KPF6 NNSH

PF6

+DI/40oC

1 h

[Bhmim]Br

[Thmim]HBr [Thmim]HPF6

1515

Brust, M,; Walker, M.; Bethell, D,;Schiffrin, D, J.; Whyman, R.J. Chem. Soc. Chem. Commun. 1994, 801-802.

Particle size distribution = 2.1 ± 1.12 nm

Synthesis of Octanethiol Protected Au-SR NPs

HAuCl4 4H2OCH3(CH2)7SH /CHCl3

NaBH4 / H2OCHCl3

CH3(CH2)7]4N+Br-

ss

ss

s

ss

1616

Nano-Gold Surface-Immobilized ILsNano-Gold Surface-Immobilized ILs

NNSH S

SS

SSSSS

+

SN

S

S

S

Ligand- Exchange

THF / rt

N

N

N

N

N

N

N

S S

SS

X = PF6

7, X = PF6

X

X

XX

X

Au

Au

1717

SN

S

S

S

N

N

N

N

N

N

N

S S

SS

7, X = PF6

X

XX

X

Au

31P NMR 19F NMR

11H, H, 3131P, and P, and 1919F of F of Au NPs-Au NPs-SupportedSupported Ionic LiquidIonic Liquid

NNSH

PF6

1818

Particle size distribution =3.1 ± 1.3 nm

TEM and UV Spectra of Au NPs-TEM and UV Spectra of Au NPs-SupportedSupported Ionic LiquidIonic Liquid

1919

Au NPs-Supported Ag(I) Complexes via Au NPs-Supported Ag(I) Complexes via Thiolated NHC Carbene LigatiorThiolated NHC Carbene Ligatior

S N N

H H

Ag

S

NN

PF6

HH Au

SNN

Au

HH

Ag

S N N

PF6

H H

Au

PF6

S N NAu

H H

Ag

NN

HH

S

SN

S

S

S

N

N

N

N

N

N

N

S S

SS

7, X = PF6

X

XX

X

Au

Ag2O& t-BuOK

CH3CN r.t./ 4h

2020

Au

S N NAu

H H

H PF6

1 H 2 H

31P NMR 19F NMRPF6

S N NAu

H H

Ag

NN

HH

S

11H, H, 3131P, and P, and 1919F ofF of Au NPs-Supported Ag(I) ComAu NPs-Supported Ag(I) Complexes via plexes via

Thiolated NHC Carbene LigatiorThiolated NHC Carbene Ligatior

2121

TEM of Au NPs-Supported Ag(I) Complexes TEM of Au NPs-Supported Ag(I) Complexes via Thiolated NHC Carbene Ligatiorvia Thiolated NHC Carbene Ligatior

SN

S

S

S

N

N

N

N

N

N

N

S S

SS

7, X = PF6

X

XX

X

Au

S N N

H H

Ag

S

NN

PF6

HH Au

SNN

Au

HH

Ag

S N N

PF6

H H

Au

2222

S N NAu

H H

Ag

SNN

PF6

HH Au

S N NAu

H H

Ag

NN

PF6

HH

S

2H

2H

NN

Ag

H H

N N

PF6

HH

PF6

S N NAu

H H2H

NNSH

PF6

HH

2H

11H NMR Spectra of Ligand, Molcular and Au H NMR Spectra of Ligand, Molcular and Au Nanoparticles seriesNanoparticles series

2323

Au-SR

IL-SH

Au-IL

Au-IL-Ag

IR Spectra of Ligand & Au Nanoparticles seriesIR Spectra of Ligand & Au Nanoparticles series

imidazole H–C–C & H–C–N bending

1240 cm-1

1251cm-1

imidazole ν (ring stretching)

1560 cm-1

1571cm-1

-SH stretching

2424

A3-coupling reactions Have attracted much attention from organic chemists for the coupling products, propargylamines, which are major skeletons or synthetically versatile building blocks for the preparation of many nitrogen-containing biologically

active compounds

J. Org. Chem. 1995, 60, 1590-1594

2525

The First Silver-CatalyzedThree-Component Coupling of Aldehyde,

Alkyne, and Amine

Chao J. L. et. al. Org. Lett., Vol. 5, No. 23, 2003,4473-4475

2626

Proposed Mechanism Proposed Mechanism for the Three –Component Couplingfor the Three –Component Coupling

C-H activation

Silver (I)

Reduction

Silver(I)

Oxidation

Chao J. L. et. al. Org. Lett., Vol. 5, No. 23, 2003,4473-4475

2727

Solvents 1 Hr 2 Hr 4 Hr

[Hmim]Br 28.96% 45.73% 4 Hr 8 Hr

69.63% 82.37%

[Hmim]PF6 78.58% 87.27% 94.78%

Propionitrile 91.31% 96.08% 97.68%

Acetonitrile 73.23% 82.57% 96.35%

DMF 30 min 1 Hr 38% 4 Hr 6 Hr

36.08% 37.59% 38% 40%

1,4-dioxane 30 min 1 Hr 20% 4 Hr 6 Hr

11% 19% 23% 25%

H

O

+NH

+

H

1-ethynylbenzene

3 % AgPF6[hmim]2

1 mL Solvents

1 mmol 1.2 mmol 1.5 mmolpiperidine

benzaldehyde

Reaction conditions: Catalyst loading =1.5 mol%; carried out on a 1 mmol scale aldehyde/amine/alkyne = 1:1.2:1.5, 1000C, 1 mL of solvents.

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HR

O+ +

R

AgPF6[hmim]21.5 mol%

Propionitrile, reflux NH

N

Entry Time Yield(%) Paper Report cat. (AgI)

Time Yield(%)

1 30 min 95 % 2 hr 96 %

2 30 min 93 % 2 hr 79 %

3 30 min

8 hr

64.3 %

71 %

No test

4. n.d No test

5. 30 min 92 %92 % 2 hr 93 %

HR

O

HO

O

H

O

H

O

H

O

Reaction conditions: Catalyst loading =1.5 mol%; carried out on a 2 mmol scale aldehyde/amine/alkyne = 1:1.2:1.5, 1000C, 1 mL of Propionitrile.

2929

HR

O+ +

R

AgPF6[hmim]23 mol%

Propionitrile, reflux NH

N

Entry Time Yield(%) Paper Report cat. (AgI)

Time Yield(%)

1 30 min 95 % 2 hr 70%

2 2 hr2 hr

6 hr6 hr

70 %

90 %

2 hr 60%

3 n.d No test

HR

O

H

O

O

Br

O

Reaction conditions: Catalyst loading = 3 mol%; carried out on a 1mmol scale aldehyde/amine/alkyne = 1:1.2:1.5, 1000C, 1 mL of Propionitrile.

3030

Three-component coupling reactions catalyzed by a reusable PS-supported

NHC–Ag(I) under solvent-free reaction conditions

Li P. , Wang L. , Zhang Y. , Wang M. Tetrahedron Letters 49 (2008) 6650–6654

3131

Au-[hmim]2AgPF6: 9 mg

1,2,4,5-tetramethylbenzene: 5 mg

d6-DMSO

4 H 2 H

1,2,4,5-tetramethylbenzene

S N NAu

H H

Ag

NN

PF6

HH

S

0.25 : 0.13 = X : 0.03725X = 0. 07164 mmol – lignad0.07164×0.5 = 0.0358 mmol- metal center0.0358/9 = 0.004 mol/g

3232

NH

+neat ,2 h

+H H

O H2C N

20 mol % Au-[hmim]2AgPF6

1 2 3 4 5 66 77 88 99

93% 97% 96% 95% 93% 93% 91% 90% 91%

80%

90%

100%

0 2 4 6 8 10

Recycle No.

Con

vers

ion(

%)

Reaction conditions: Catalyst loading = 20mol%;para-formaldehyde(1.0mmol),piperidine(1.1mmol) phenylacetylene(1.1mmol) at room temperature for 24 h

3333

ConclusionsConclusions

1.We have developed a method to successfully immobilize (NHC)2AgPF6 onto surfaces of Au NPs was characterized by 1H-NMR,IR,TEM.

2.The air- and water- stable catalyst [Ag(hmim)2]PF6 was characterized by 1H- and 13C NMR, LC-MS, IR.

3. We have successfully demonstrated the catalytic activity of the Ag(I) complex for three component (aldehyde, alkyne, and amine) coupling reaction.

4. The Au NPs- Ag(I) hybrid catalysts can be easily recovered and reused many times without significant loss of reactivity.

3434

3535

Immobilization of AgPFImmobilization of AgPF66(NHC) onto(NHC) onto

Surfaces of Au-NPsSurfaces of Au-NPs

H

2H

2H

S N N

PF6

Au

H H

H

S N NAu

H H

Ag

NN

PF6

HH

S

S N NAu

H H

Ag

SNN

PF6

HH Au

*H2O

*H2O

*DMSO

*DMSO

3636

IL-SH

Au-IL-Ag

Au-IL

3737

NH

+

1.1 mmol 1.1mmol

neat ,20 h+ piperidine 1-ethynylbenzene

H H

O

formaldehyde

1mmol

H2C N

2 mol % Au-[hmim]2AgPF6

11 22

95%95% 92%92%

Li P. , Wang L. , Zhang Y. , Wang M. Tetrahedron Letters 49 (2008) 6650–6654

3838