In Search of Cationic Germanium(II)−Transition Metal Complexes L²Ge⁺W(CO)₅ and L²Ge⁺W(CO)₄Ge⁺L²

New germanium(II)−tungsten complexes [L2(X)Ge]nW(CO)6-n (L2 = NPhC(Me)CHC(Me)NPh, n = 1, X = OTf (2); n = 2, X = Cl (13)) have been synthesized and characterized by
X-ray crystallography. In compound 2 the triflate was found to be very weakly coordinating
to the germanium in the solid state, and this result is confirmed by DFT calculations. All
the spectroscopic data are consistent with the L2(X)Ge ligands being good σ-donors and poor
π-acceptors in these complexes, similar to the phosphine ligands in homologous R3P
complexes. Starting from the chlorogermanium(II)−tungsten complexes (L2(Cl)Ge)nW(CO)6-n
(n = 1 (1), n = 2 (13)), metathesis reactions with halide or weakly coordinating anions A-
(A- = TfO-, BPh4-, PF6-) have been investigated as a general approach to obtain the cationic
germanium species [L2Ge+]nW(CO)6-n. In the case of A- = TfO-, spontaneous dissociation
of the anion leading to an equilibrium between a neutral and a cationic tetracoordinated
germanium species is observed in coordinating solvents. Treatment of L2(X)Ge with MX3
(M = Ga, X = Cl; M = In, X = I) afforded the neutral complexes L2MX2 (M = Ga (7) and In
(8)) by ligand transfer reactions. The crystal structure of 8 was determined by X-ray structure
analysis.