Multiple ethylene activation by heteroleptic L(Cl)Ga-substituted germylenes.

Ethylene insertion into the Ga-Ge bond of the L(Cl)Ga-substituted germylene LGa(μ-Cl)GeDMP 1 (L = HC(C(Me)NAr) 2 , Ar = 2,6- i Pr 2 C 6 H 3 ; DMP = 2,6-Mes 2 C 6 H 3 , Mes = 2,4,6-Me 3 C 6 H 2 ) at ambient temperature is followed by dimerization of the as-formed germylene to give the digermene 3, which further reacted with ethylene in a [2 + 2] cycloaddition to give the 1,2-digermacyclobutane 4. In marked contrast, the amino-substituted germylene L(Cl)GaGeN(SiMe 3 )Ar 2 reacted directly to the 1,2-digermacyclobutane 5. Quantum chemical calculations confirmed the assumed reaction mechanism, hence demonstrating the crucial role of the substituent on the reaction mechanism.