Reactivity of main-group–transition-metal bonds. Part V. Kinetics of reactions of halogens and interhalogens with pentacarbonyl(trimethylstannyl)manganese, tricarbonyl(η-cyclopentadienyl)(trimethylstannyl)molybdenum, and dicarbonyl(η-cyclopentadienyl)(trimethylstannyl)iron, including the effects of solvents on reactivity

Abstract

The kinetics of the reactions of [Mn(CO)₅(SnMe₃)]. [Mo(cp)(CO)₃(SnMe₃)]. and [Fe(cp)(CO)₂(SnMe₃)](cp =η-cyclopentadienyl) wiih bromine in tetrachloromethane (first compound), with iodine monochloride and iodine monobromide in tetrachloromethane (first two compounds), and with iodine in various solvents (all three compounds) have been studied. Bromine is ca. 4 000 times more reactive than I₂, the iodine monohalides form charge-transfer complexes prior to reaction and appear to react at approximately the same rate as I₂, and the reaction rate depends on solvent polarity. The reaction is akin to an aromatic substitution: a mechanism involving an intermediate complex that is stabilised by vertical hyperconjugation is in accord with the experimental results.