Dimetallagermanes of molybdenum and tungsten: synthesis, structure and reactions

Abstract

Reaction of the trichlorogermyl complexes CpM(CO)₃GeCl₃ 3a or 3b with Li[CpM(CO)₃] 2a or 2b, which were obtained from CpM(CO)₃H 1a or 1b and LiBuⁿ, afforded the dimetalladichlorogermanes [CpM(CO)₃]₂GeCl₂ 4a or 4b (Cp = C₅H₅; a M = Mo; b M = W). Similarly, treatment of Cp*Mo(CO)₃GeCl₃ 3c with K[Cp*Mo(CO)₃] 2c yielded selectively [Cp*Mo(CO)₃]₂GeCl₂ 4c (Cp* = C₅Me₅). Complex 3c was obtained from Cp*Mo(CO)₃H 1c in two steps. The first step involved an insertion of GeCl₂ into the molybdenum–hydrogen bond of 1c to give the dichlorogermyl complex Cp*Mo(CO)₃GeCl₂H 5c followed by chlorination of 5c with CCl₄. The dimetalladichlorogermanes 4a–4c contain two reactive sites for further functionalization, the transition-metal centers and the germanium atom. This has been demonstrated by the CO/PMe₃ ligand exchange reaction of 4a to give [Cp(CO)₃Mo(µ-GeCl₂){trans-Mo(CO)₂(PMe₃)Cp}] 6a and the substitution reaction of 4a with LiAlH₄ to afford the dimetallagermane [CpMo(CO)₃]₂GeH₂ 7a. The crystal structures of 4a, 4b and 6a have been reported.