Determination of the heat of formation of trimethylindium and calculation of the mean In—CH3 bond dissociation energy

Abstract

The enthalpy of reaction of In(CH₃)₃,c with a chloroform solution of bromine is −162.5 kcal mole⁻¹. With this value ΔH_f⁰₂₉₈[In(CH₃)3,c] = 29.5 kcal mole⁻¹ and ΔH_f⁰₂₉₈[In(CH₃)₃,g] = 41.1 kcal mole⁻¹. Combining the latter with ΔH_f⁰₂₉₈[CH₃,g] = 33.2 kcal mole⁻¹ and ΔH_f⁰₂₉₈[In,g] = 58.2 kcal mole⁻¹ then gives E(In—CH₃) = 38.9 kcal mole⁻¹. From previous kinetic studies D[(CH₃)₂In—CH₃] + D[In—CH₃] = 87.9 kcal mole⁻¹. Hence D[CH₃In—CH₃] = 28.8 kcal mole⁻¹.