Hanan Abdou

Date of Award

5-2001

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

Advisor

Alice E. Bruce

Second Committee Member

Mitchell R.M. Bruce

Third Committee Member

François G. Amar

Abstract

Chemical oxidation of dinuclear gold(I) thiolates of the formula LLAu2(SC6H4CH3)2 [LL= dppp, bis(dipheny1phosphine)propane and dppb, bis(dipheny1phosphine)butane] and dinuclear gold(I) thiolate complexes with bridging a propane dithiolate ligand of the formula LLAu2(SC3H6S) [LL = dppp and dppb] was carried out using the mild oxidizing agent, ferrocenium, [Cp2Fe]PF6). Spectroscopic studies and elemental analysis showed the formation of gold(I) clusters, disulfide, and ferrocene as products of this oxidation reaction. The clusters, [(dppp)AU2(SC6H4CH3)](PF6) and [(dppb)Au2(SC6H4CH3)](PF6) were isolated after the chemical oxidation of dpppAu2(SC6H4CH3)2 and dpppAu2(SC6H4CH3)2. Structures of the isolated clusters are proposed on the basis of 'H NMR, 31P NMR, elemental analysis and by comparison to other clusters previously characterized in our lab. Cyclic voltammetry studies of the four isolated clusters showed a peak at -1.6 V vs. Ag/AgCl; however the starting gold(I) thiolate complexes showed two peaks at -0.6 and 1.5 V vs. Ag/AgCl. Thiolate-disulfide exchange reactions of the isolated clusters with (SC6H4Cl)2 were studied and compared with the starting gold(I) thiolate complexes. The gold cluster [(Ph3PAu)4(SC6H4CH3)2](PF6)2 was chosen for kinetic studies because it was well characterized and it was known to react with disulfide (ClC6H4SSC6H4Cl). Kinetic data was obtained by monitoring the reaction by 'H NMR. The plots of In[cluster] (M) versus time (s) showa a linear relationship, which is consistent with first order in cluster concentration. The plots of In [disulfide] (M) versus time (s) show a linear relationship, which is consistent with first order in disulfide concentration. The data are consistent with the rate law: Rate = k[Ph3PAu)4(SC6H4CH3)22+][ClC6H4SSC6H4Cl]. The results showed that gold(I) clusters reacted faster than the neutral gold(I) thiolate complexes which suggest that Au … Au interactions play a role in the disulfide exchange.

Download

Share