Halide substitution reactions of the germylidyne complexes trans-[X(dppe)2WGe(η1-Cp*)] (X = Cl, I; dppe = Ph2PCH2CH2PPh2; Cp* = C5Me5)

The first reactions of the germylidyne complexes trans-[X(dppe)(2)Wequivalent toGe(eta(1)-Cp*)](.)[toluene] (1-(ClC7H8)-C-., X = Cl; 1-(IC7H8)-C-., X = I) with nucleophiles and electrophiles are reported. Treatment of 1-(IC7H8)-C-. with KBH4 in refluxing THF affords selectively the hydrido-germylidyne complex trans- [H(dppe)(2)W=Ge(eta(1)-Cp*)] (2). Similarly, metathetical exchange of 1-(IC7H8)-C-. with an excess of MY (M = Na, K; Y = NCO, N-3, NCS, CN) gives the pseudohalide complexes trans-[Y(dppe)(2)Wequivalent toGe(eta(1)-Cp*)](.)x(toluene) (3a, Y = NCO, x = 0; 3b, Y = N-3, x = 0; 3c(.)C(7)H(8), Y = NCS, x = 1; 3d(.)0.5C(7)H(8), Y = CN, x = 0.5). Chloride abstraction from 1-(ClC7H8)-C-. with Li[B(C6F5)(4)](.)2.5Et(2)O yields in the presence of acetonitrile the first cationic germylidyne complex, trans- [(MeCN)(dppe)(2)W=Ge(eta(1)-Cp*)] [B(C6F5)(4)] (4). All new complexes were well characterized. The molecular structures of 2(.)1.5C(6)D(6), 3a(.)THF, 3d-0.5C(7)H(8), 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-C-Cp* = 172.0(1)-176.8(1)degrees) and a eta(2)-bonded Cp* substituent.