Electron-Rich Trichlorogermyl Complexes of Molybdenum and Tungsten Bearing a Cyclopentadienyl Ligand: Synthesis, Crystal Structures, and Cyclic Voltammetric Studies

Oxidative decarbonylation of cis-(η5-C5R5)M(CO)2(PMe3)Cl (1a−1d) (a, R = H, M = Mo; b, R = H, M = W; c, R = Me, M = Mo; d, R = Me, M = W) with 1 equiv of PhICl2 yields selectively the M(IV) complexes (η5-C5R5)M(CO)(PMe3)Cl3 (2a−2d). Complex 1c reacts with 1.5 equiv of PhICl2 and complex 2d with 0.5 equiv of PhICl2 to give respectively Cp*Mo(PMe3)Cl4 (3c) and Cp*W(PMe3)Cl4 (3d) (Cp* = C5Me5) in quantitative yield. Complex 2d can also be prepared from Cp*W(CO)3Cl (4d) in two steps. The first step involves an oxidation of 4d with 1 equiv of PhICl2 to yield selectively Cp*W(CO)2Cl3 (5d) followed by a CO ligand exchange reaction of 5d with PMe3. Reduction of 2a−2d with Na/Hg affords in the presence of PMe3 the M(II) chloro complexes trans-(η5-C5R5)M(CO)(PMe3)2Cl (6a−6d) in high yield. Complexes 6a−6d rapidly insert GeCl2 into the metal−chlorine bond to give selectively the “electron-rich” trichlorogermyl complexes trans-(η5-C5R5)M(CO)(PMe3)2GeCl3 (7a−7d). The crystal structures of CpW(CO)(PMe3)Cl3·MeCN (Cp = C...