Fluoro Complexes of Permethyltantalocene, Cp*2TaF3 and [Cp*2TaF2][BF4]: Facile Formation of a Tetrafluoroborate Complex via Corrosion of Borosilicate Glass

Abstract

The trihydride complex Cp*2TaH3 is a convenient precursor to a series of halide derivatives, which include unusual examples of organometallic fluoride complexes. Most interestingly, reaction of Cp*2TaH3 with (C5H5N)(HF)x affords the trifluoride complex Cp*2TaF3 when carried out in a plastic vessel, but the tetrafluoroborate complex [Cp*2TaF2][BF4] when performed in a borosilicate glass vessel. In contrast, reaction of Cp*2TaH3 with [Et3N(HF)3] results in cleavage of one of the pentamethylcyclopentadienyl ligands to yield the half-sandwich complex [Et3NH][Cp*TaF5]. Cp*2TaF3 and [Cp*2TaF2][BF4] may be readily interconverted. Thus, treatment of Cp*2TaF3 with either Et2O·BF3 or LiBF4 yields [Cp*2TaF2][BF4], while reaction of the latter complex with excess NaF regenerates Cp*2TaF3. Furthermore, Cp*2TaF3 is converted to the cyano fluoride complex Cp*2Ta(CN)2F upon reaction with excess Me3SiCN. Sequential replacement of the hydride ligands of Cp*2TaH3 is observed in the reaction with MeI to give Cp*2TaH2I and Cp...