Halide Substitution Reactions of the Germylidyne Complexes trans-[X(dppe)2W⋮Ge(η1-Cp)] (X = Cl, I; dppe = Ph2PCH2CH2PPh2; Cp = C5Me5)

The first reactions of the germylidyne complexes trans-[X(dppe)2W⋮Ge(η1-Cp*)]·[toluene] (1-Cl·C7H8, X = Cl; 1-I·C7H8, X = I) with nucleophiles and electrophiles are reported. Treatment of 1-I·C7H8 with KBH4 in refluxing THF affords selectively the hydrido−germylidyne complex trans-[H(dppe)2W⋮Ge(η1-Cp*)] (2). Similarly, metathetical exchange of 1-I·C7H8 with an excess of MY (M = Na, K; Y = NCO, N3, NCS, CN) gives the pseudohalide complexes trans-[Y(dppe)2W⋮Ge(η1-Cp*)]·x(toluene) (3a, Y = NCO, x = 0; 3b, Y = N3, x = 0; 3c·C7H8, Y = NCS, x = 1; 3d·0.5C7H8, Y = CN, x = 0.5). Chloride abstraction from 1-Cl·C7H8 with Li[B(C6F5)4]·2.5Et2O yields in the presence of acetonitrile the first cationic germylidyne complex, trans-[(MeCN)(dppe)2W⋮Ge(η1-Cp*)][B(C6F5)4] (4). All new complexes were well characterized. The molecular structures of 2·1.5C6D6, 3a·THF, 3d·0.5C7H8, and 4 were determined by single-crystal X-ray diffraction studies. The germylidyne complexes reveal very short W−Ge distances (d W - Ge = 229.91(9)−231.84(6) pm), an almost linear geometry at the triply bonded germanium atom (W−Ge−CCp* = 172.0(1)−176.8(1)°) and a η1-bonded Cp* substituent.