Alkylation of tricarbonyliron complexes by trimethylsilyl cyanide: synthetic and kinetic studies

Abstract

Trimethylsilyl cyanide has been shown to be a synthetically useful reagent for the alkylation of tricarbonyl(η⁵-cyclohexadienyl)iron(1+) salts, particularly in cases where the reactive terminus of the dienyl system bears an alkyl substituent. The reaction proceeds via the isocyanide isomer, with a rate-limiting pre-equilibration of the reagent. In cases where reactive metal complexes were used, the rate of reaction was proportional to the concentration of Me₃SiCN, and was independent of both the nature and concentration of the dienyl salt. In the case of the deactivated 2-methoxy substituted dienyl salt, non-linear rate plots indicated a change in the rate-limiting step.