Metal Activation of a Germylenoid, a New Approach to Metal–Germanium Triple Bonds: Synthesis and Reactions of the Germylidyne Complexes [Cp(CO)2M≡Ge–C(SiMe3)3] (M = Mo, W)

The reactions of the germylenoid Li(THF) 3 GeCl 2 C(SiMe 3 ) 3 with the carbonyl metalates Li[CpMo(CO) 3 ] and K[CpW(CO) 3 ] (Cp = η 5 -C 5 H 5 ) in toluene afford selectively the germylidyne complexes [Cp(CO) 2 M≡Ge–C(SiMe 3 ) 3 ] ( 1-Mo, M = Mo; 1-W, M = W). The compounds 1-Mo and 1-W rapidly add 1,3,4,5-tetramethylimidazol-2-ylidene (Im-Me 4 ) at the electrophilic germanium center to give the zwitterionic germylidene complexes [Cp(CO) 2 M═Ge(Im-Me 4 ){C(SiMe 3 ) 3 }] ( 2-Mo, M = Mo; 2-W, M = W). The molecular structures of 1-Mo/1-W and 2-Mo/2-W were determined by single-crystal X-ray diffraction studies, and the structural and spectroscopic features of all complexes are discussed.