Reactivity of a N-Coordinated Germylene-Borane Complex: From Ge→B to Ge→Ga Coordination

Reactivity studies of the Ge^II →B complex L(Cl)Ge⋅BH₃ (1; L=2-Et₂ NCH₂ -4,6-tBu₂ -C₆ H₂ ) were performed to determine the effect on the Ge^II →B donation. N-coordinated compounds L(OtBu)Ge⋅BH₃ (2) and [LGe⋅BH₃ ]₂ (3) were prepared. The possible tuning of the Ge^II →B interaction was proved experimentally, yielding compounds 1-PPh₂ -8-(LGe)-C₁₀ H₆ (4) and L(Cl)Ge⋅GaCl₃ (5) without a Ge^II →B interaction. In 5, an unprecedented Ge^II →Ga coordination was revealed. The experimental results were complemented by a theoretical study focusing on the bonding in 1-5. The different strength of the Ge^II →E (E=B, Ga) donation was evaluated by using energy decomposition analysis. The basicity of different L(X)Ge groups through proton affinity is also assessed.