Trifluorophosphine as a Bridging Ligand in Homoleptic Binuclear Nickel Complexes

The stable tetrahedral derivative Ni(PF3)(4) is reported to generate binuclear Ni-2(PF3)(n) ions in its mass spectrum emerging from ion molecule reactions. Theoretical studies on such binuclear complexes indicate Ni-2(PF3)(7) to be energetically unfavorable with respect to decomposition into Ni(PF3)(4) + Ni(PF3)(3). However, viable rather unsymmetrical structures with two PF3 bridges for Ni-2(PF3)(n) (n = 6, 5, 4) are reported here as well as a triply semibridged Ni-2(PF3)(5) structure. The nickel nickel distances in these Ni-2(PF3)(n) derivatives suggest a formal double bond (251 angstrom). a formal triple bond (226 angstrom), and a formal double bond (234 angstrom) for n = 6, 5, and 4, respectively. The mononuclear Ni(PF3)(n) derivatives are predicted to have tetrahedral, trigonal planar, and bent (139 degrees) structures for n = 4, 3, and 2. respectively.