Electronic effects on the rates of coupled two-electron/halide self-exchange reactions of substituted ruthenocenes.
The complexes (MemCp)(MenCp)Ru (m,n = 1,1; 0.4; 0.5; 1.5) have been synthesized along with the corresponding halometalloceniums [(MemCp)(MenCp)RuX]+ (X = Cl, Br, I). The two-electron/halide transfer self-exchange kinetics have been determined and compared to those of the Cp2Ru/[Cp2RuX]+ parent system. Methylation decreases the rate of exchange monotonically, and plots of ln(kex) vs number of methyl groups are linear for constant X. It is concluded that steric effects do not contribute significantly to the observed kinetics. Thermodynamic studies of halide substitution equilibria support the conclusion that the electronic effects of methylation are essentially additive.
Shea
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TM
Department of Chemistry, Wesleyan University, Middletown, Connecticut 06459, USA.
Westmoreland
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TD