Molecular and Gold Nanoparticles Supported N-Heterocyclic Carbene Silver(I) Complexes – Synthesis, Characterization and Catalytic Applications 學 生 :王趙增 指導老師 : 于淑君 博士 2009 / 04 / 27 Department of Chemistry & Biochemistry Chung Cheng University

N-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

N-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.

The Applications of Ag(I) NHC Silver(I)-Carbene Complexes as Carbene Transfer Agents Addition of arenes to imines Aza-Diels-Alder reaction Asymmetric aldol reaction Barbier-Grignard-type reaction

The First Silver(I)-Carbene Complexes Arduengo.A.J,et.al. Organometallics 1993, 21, 3405-3409

Silver(I)-Carbene Complexes as Carbene Transfer Agents Wang, H. M. J.; Lin, I. J. B. Organometallics 1998, 17, 972-975

Motivation Using NHCs ligand to replace phosphine ligand in organomatallic catalysis. -Immobilization of NHC- Ag(I) complexs onto Au Nanoparticles Recyclable catalysts and their Applications in solvent-free system. Developing a homogeneous catalyst for aldehyde alkyne and amine coupling.

Preparation of [Ag(hmim)2]PF6 Complex Experimental Preparation of [Ag(hmim)2]PF6 Complex

1H NMR Spectra of [Hmim]HPF6, [Ag(hmim)2]PF6 *H2O *DMSO *H2O 2H 2H *DMSO

13C NMR Spectra of [Hmim]HPF6, [Ag(hmim)2]PF6 *DMSO C *DMSO c

Change Temperature 1H NMR Spectra of [Ag(hmim)2]PF6 Temp.:250C Temp.:100C H H

ESI-MS Spectrum of [Ag(hmim)2]PF6

Ionic Liquids As Stabilizing Agents for NPs Addition of (a) HCl, (b) HBr, (c) HBF4, (d) HI,and (e) HPF6. 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.

Synthetic Strategy

Synthesis of Octanethiol Protected Au-SR NPs Particle size distribution = 2.1 ± 1.12 nm Brust, M,; Walker, M.; Bethell, D,; Schiffrin, D, J.; Whyman, R.J. Chem. Soc. Chem. Commun. 1994, 801-802.

Nano-Gold Surface-Immobilized ILs

1H, 31P, and 19F of Au NPs-Supported Ionic Liquid 31P NMR 19F NMR

TEM and UV Spectra of Au NPs-Supported Ionic Liquid Particle size distribution =3.1 ± 1.3 nm

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

Thiolated NHC Carbene Ligatior 1H, 31P, and 19F of Au NPs-Supported Ag(I) Complexes via Thiolated NHC Carbene Ligatior 1 H 2 H 31P NMR 19F NMR

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

1H NMR Spectra of Ligand, Molcular and Au Nanoparticles series

IR Spectra of Ligand & Au Nanoparticles series Au-SR IL-SH Au-IL Au-IL-Ag imidazole H–C–C & H–C–N bending 1240 cm-1 1251cm-1 imidazole ν (ring stretching) 1560 cm-1 1571cm-1 -SH stretching

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

The First Silver-Catalyzed Three-Component Coupling of Aldehyde, Alkyne, and Amine Chao J. L. et. al. Org. Lett., Vol. 5, No. 23, 2003,4473-4475

for the Three –Component Coupling Proposed Mechanism for the Three –Component Coupling C-H activation Silver(I) Oxidation Silver (I) Reduction Chao J. L. et. al. Org. Lett., Vol. 5, No. 23, 2003,4473-4475

Solvents 1 Hr 2 Hr 4 Hr [Hmim]Br 28.96% 45.73% 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 38% 6 Hr 36.08% 37.59% 40% 1,4-dioxane 20% 11% 19% 23% 25% 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.

Entry Time Yield(%) Paper Report cat. (AgI) 1 30 min 95 % 2 hr 96 % 2 93 % 79 % 3 8 hr 64.3 % 71 % No test 4. n.d 5. 92 % 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.

Entry Time Yield(%) Paper Report cat. (AgI) 1 30 min 95 % 2 hr 70% 2 70 % 90 % 60% 3 n.d No test 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.

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

1,2,4,5-tetramethylbenzene: 5 mg d6-DMSO 0.25 : 0.13 = X : 0.03725 X = 0. 07164 mmol – lignad 0.07164×0.5 = 0.0358 mmol- metal center 0.0358/9 = 0.004 mol/g Au-[hmim]2AgPF6: 9 mg 1,2,4,5-tetramethylbenzene: 5 mg

1 2 3 4 5 6 7 8 9 93% 97% 96% 95% 91% 90% Reaction conditions: Catalyst loading = 20mol%;para-formaldehyde(1.0mmol),piperidine(1.1mmol) phenylacetylene(1.1mmol) at room temperature for 24 h

Conclusions 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.

Immobilization of AgPF6(NHC) onto Surfaces of Au-NPs *H2O *DMSO 2H H *DMSO *H2O 2H

IL-SH Au-IL Au-IL-Ag

1 2 95% 92% Li P. , Wang L. , Zhang Y. , Wang M. Tetrahedron Letters 49 (2008) 6650–6654