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.