Electron-rich trichlorogermyl complexes of molybdenum and tungsten bearinga cyclopentadienyl ligan: Synthesis, crystal structures, and cyclic voltammetric studies

Oxidative decarbonylation of Cis-(eta(5)-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(TV) complexes (eta(5)-C5R5)M(CO)( PMe3)Cl-3 (2a-2d). Complex Ic reacts with 1.5 equiv of PhICl2 and complex 2 d with 0.5' equiv of PhICl2 to give respectively Cp*Mo(PMe3)Cl-4 (3c) and C p*W(PMe3)Cl-4 (3d) (Cp* = C5Me5) in quantitative yield. Complex 2d can also be prepared from Cp*W(C0)(3)Cl (4d) in two steps. The first step involves an oxidation of 4d with 1 equiv of PhICl2 to yield selectively Cp*W(C0)(2)C l-3 (5d) followed by a CO ligand exchange reaction of 5d with PMe3. Reducti on of 2a-2d with Na/Hg affords in the presence of PMe3 the M(II) chloro com plexes trans-(eta(5)-C5R5)M(CO)(PMe3)(2)Cl (6a-6d) in high yield. Complexes 6a-6d rapidly insert GeCl2 into the metal-chlorine bond to give selectivel y the "electron-rich" trichlorogermyl complexes trans-(eta(5)-C5R5)M(CO)(PM e3)(2)GeCl3 (7a-7d). The crystal structures of CpW(CO)(PMe3)Cl-3. MeCN (Cp = C5H5) (2b-1), CpW(CO)(PMe3)C13 0.5THF (2b-2), ed, and 7b are presented, a nd the cyclic voltammetric data of the complexes 6b-6d and 7a-7d are compar ed.