INSERTION OF GECL2 INTO GROUP-VI TRANSITION-METAL CHLORINE BONDS - SYNTHESIS, SPECTROSCOPY AND STRUCTURE OF MOLYBDENUM AND TUNGSTEN TRICHLOROGERMYL COMPLEXES

An efficient method for the synthesis of trichlorogermyl complexes is reported involving the insertion of GeCl2 into the metal-chlorine bond of Group VI transition metal complexes bearing a cyclopentadienyl (Cp ) or a pentamethylcyclopentadienyl (Cp) ligand. This is demonstrated by the reactions of the complexes (eta 5-C5R5)M(CO)(3)Cl(1a-1c) (a: R = H, M = Mo, b: R = H, M = W; c: R = Me, M = W) and cis-CpM(CO)(2)(L)C l (3a, 56) (3a: M = Mo, L = PMe3 56: M = W, L = EtNC) with GeCl2(dioxa ne), which afford selectively the trichlorogermyl complexes (eta 5-C5R 5)M(CO)(3)GeCl3 (2a-2c) and cis-CpM(CO)(2)(L)GeCl3 (cis-4a, 6b), respe ctively. The complex cis-CpMo(CO)(2)(PMe3)GeCl3 (cis-4a) isomerizes in solution and in solid-state to trans-CpMo(CO)(2)(PMe3)GeCl3 (trans-4a ). The GeCl2-insertion reaction offers a more convenient method for th e synthesis of Group VI transition metal trichlorogermyl complexes as shown by a comparison of the syntheses of cis-Cp W(CO)(2)(EtNC)GeCl3 (6c) from cis-Cp W(CO)(2)(EtNC)Cl (5c) and GeCl2(dioxane) or from Na[ Cp W(CO)(2)(EtNC)] (7c) and GeCl4. The crystal structures of the tric hlorogermyl complexes 2a, 2c, trans-4a and 6c are reported. (C) 1997 E lsevier Science S.A.