Dimetallagermanes of molybdenum and tungsten: synthesis, structure and reactions

摘要

Reaction of the trichlorogermyl complexes CpM(CO)(3)GeCl3 3a or 3b with Li[CpM(CO)(3)] 2a or 2b, which were obtained from CpM(CO)(3)H 1a or 1b and LiBun, afforded the dimetalladichlorogermanes [CpM(CO)(3)](2)GeCl2 4a or 4b (Cp = C5H5; a M = Mo; b M = W). Similarly, treatment of Cp*Mo(CO)(3)GeCl3 3c with K[Cp*Mo(CO)(3)] 2c yielded selectively [Cp*Mo(CO)(3)](2)GeCl2 4c (Cp* = C5Me5). Complex 3c was obtained from Cp*Mo(CO)(3)H 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)(3)GeCl2H 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)(3)Mo(mu-GeCl2) {trans-Mo(CO)(2)(PMe3)Cp}] 6a and the substitution reaction of 4a with LiAlH4 to afford the dimetallagermane [CpMo(CO)(3)](2)GeH2 7a. The crystal structures of 4a, 4b and 6a have been reported. [References: 61]