INTERCHANGE BETWEEN MONOLAYERS ON GOLD FORMED FROM UNSYMMETRICAL DISULFIDES AND SOLUTIONS OF THIOLS - EVIDENCE FOR SULFUR SULFUR BOND-CLEAVAGE BY GOLD METAL

Reaction of an unsymmetrical disulfide, HO(CH2)16SS(CH2)3CF3, with a gold surface yields a self-assembled monolayer containing approximately equal proportions of the two different thiolate groups. The S(CH2)3CF3 group in these mixed monolayers is replaced by S(CH2)16CN on exposure to a solution of HS(CH2)16CN in ethanol about 10(3) times more rapidly than the S(CH2)16OH group, although approximately 70-80 % of the latter group is eventually replaced. These observations support the conclusion that disulfides adsorb on the surface of gold with cleavage of their sulfur-sulfur bond to form a new species (a gold thiolate). The two thiolates formed from a single disulfide behave as independent entities in their subsequent reactions.