Germylene and Silylene Complexes of Molybdenum via E−H (E = Ge, Si) Bond Activations: Steric Influences on Intramolecular MoH···E Interactions

Reactions of Cp*(dmpe)Mo(η3-CH2Ph) with organogermanes (RR′GeH2) afforded germylene complexes Cp*(dmpe)Mo(H)GeRR′ (RR′ = Ph2 (2), Et2 (3), (Mes)H (4), (tBu)H (5)). Compound 2 does not possess an intramolecular H···Ge interaction of the type exhibited by its silicon analogue and by 3. The existence of such interactions appears to depend on the steric properties of substituents on the Ge (or Si) atom. For comparison, a silylene complex was prepared by reaction of 9-silafluorene with 1, to give Cp*(dmpe)Mo(H)Si(C12H8), which on the basis of NMR spectroscopy does not possess a significant Si···H interaction.