Kinetics and mechanism of dimerization of arylmercurials

The kinetics of dimerization of arylmercurials XC 6 H 4 HgCl (X H, p ‐CH 3 , m ‐CH 3 , p ‐Cl, m ‐OCH 3 , m ‐CO 2 C 2 H 5 , and o ‐OCH 3 ) in the presence of [ClRh(CO) 2 ] 2 was studied in hexamethylphosphoramide (HMPA). The experimental rate law obtained is − d [ArHgCl]/ dt = k [ArHgCl] 2 . The kinetic parameters of these reactions have been reported, and the variation, therein, has been explained on the basis of steric effect of substituents. The apparent activation energy E is linearly proportional to pre‐exponential factor lnA. A most plausible mechanism has been proposed on the basis of experimental results. © 1993 John Wiley & Sons, Inc.