494 - Solvent dielectric effect on metal assisted thiolate-disulfide exchange: No free thiolate

Asela Chandrasoma, Alice E. Bruce, Mitchell R. M. Bruce Department of Chemistry, University of Maine, Orono, ME, United States

Gold(I) and zinc(II) thiolate complexes have been found to assist thiolate-disulfide
exchange reactions. Metal assisted thiolate disulfide exchange reactions were
modeled in Gaussian 03 (B3LYP level of theory using basis sets 6-31G(d,p), and
LANL2DZ for metals Zn and Au, respectively). The results indicate that metal thiolates interact directly across the disulfide bond, forming a polar, four- atom cyclic transition state.
During the exchange, free thiolate does not form; consistent with experimental
data. The charge separation is greater in the four-atom transition state than in
the ground state suggesting that the transition state would be more stabilized
in higher dielectric media than in gas phase. Thus as the dielectric environment is increased, the activation barrier is lowered, increasing the reaction rates. A comparison with
thiolate-disulfide exchange in the absence of a metal will also be presented.

Monday, August 23, 2010 08:00 PM
Sci-Mix (08:00 PM - 10:00 PM)
Location: Boston Convention & Exhibition Center
Room: Hall C

Tuesday, August 24, 2010 07:00 PM
General Inorganic Chemistry (07:00 PM - 09:00 PM)
Location: Boston Convention & Exhibition Center
Room: Hall C