Electron Affinities and Gas-Phase Acidities of Organogermanium and Organotin Compounds

The electron affinities have been measured for trimethylgermanium and trimethyltin radicals as 31.9 ± 0.7 and 39.2 ± 1.5 kcal/mol, respectively, using electron photodetachment spectroscopy. The acidities (ΔH°_acid) for the corresponding hydrides (Me₃GeH and Me₃SnH) have been bracketed as 361.5 ± 2.8 and 349 ± 2 kcal/mol. From the electron affinities and the acidities, the D°(Me₃MH) are derived as 79.8 ± 3.5 and 75 ± 3.5 kcal/mol, respectively. These physical properties are compared with the properties of the group IVA through group VIIA binary hydrides and methyl-substituted compounds. The electron affinities of the group IVA compounds do not conform to the regular pattern; some of the reasons for this are discussed.