Reduction of a coordinated acetonitrile ligand: Synthesis of an ethylimido complex of tungsten

Article abstract of DOI:10.1021/om970829v

Treatment of the dinitrogen complex W(N₂)₂(dppe)₂ (1; dppe = 1,2-bis(diphenylphosphino)-ethane) with trifluoromethanesulfonic acid yields the novel hydrazido complex [W(N₂H₂)-(OTf)(dppe)₂]⁺[OTf] ^- (2; OTf = CF₃SO₃^-). The triflato ligand is readily displaced by other ligands and coordinating solvents. The triflato complex 2 yields the complex [W(N₂H₂)-(NCCH₃)(dppe)₂] ²⁺ (5), when it is dissolved in acetonitrile, and 5 is readily deprotonated by a variety of bases to give the acetonitrile-dinitrogen complex W(N₂)(NCCH₃)(dppe)₂ (3). Complex 3 is protonated at the β-carbon by tetrafluoroboric acid, resulting in the reduction of the coordinated nitrile to give the novel imido complex [WF(NCH₂CH₃)(dppe)₂]⁺[BF ₄]^- (4). The X-ray crystal structure of the imido complex 4 reveals an effectively linear W-N-C bond (171.8°) in the imido ligand with a W-N bond length of 1.741(4) A?.