Reactivity of main-group–transition-metal bonds. Part IV. Kinetics of iodination of compounds containing Group 4B elements bonded to molybdenum, manganese, and iron: effects of structure on reactivity

Abstract

Rate coefficients have been determined for the reactions in tetrachloromethane of iodine with [Fe(cp)(CO)₂(MMe₃)](M = Si, Ge, or Sn), [Mo(cp)(CO)₃(SnR₃)](R = Me, Bu, or Ph), [Fe(cp)(CO)₂(SnR₃)](R = Me, Bu, or Ph), [Mn(CO)₅(SnR₃)](R = Me, Et, or C₆H₁₁), [Mn(CO)₅(MMe₃)](M = Si, Ge, Sn or Pb), and [Mo(η-C₅H₄Me)(CO)₃(SnPh₃)]. Alkyl groups on the Group 4B element influence reactivity as expected from their electronic properties rather than their steric effects. The reactivity of the compounds increases as silicon is replaced by germanium, tin, and lead. This is a consequence of vertical hyperconjugation and increasing stability of the MMe₃⁺ion (M = Si, Ge, Sn, or Pb).