Novel oxo-bridged dinuclear molybdenum(II) complexes: reaction of (BF4)2 with aromatic isocyanides. X-Ray crystal structures of (BF4)2 (R = 2,6-Me2C6H3) and (BF4) (R = 2,4,6-Me3C6H2)

Article abstract of DOI:10.1016/0022-328X(94)05380-T

Treatment of the dinuclear molybdenum complex (BF4)2 with aromatic isocyanides (RNC) gave an oxo-bridged dinuclear molybdenum(II) complex, (BF4)2 (1), and a mononuclear molybdenum(IV) complex, (BF4) (2) (R = 2,6-dimethylphenyl (Xyl) or 2,4,6-trimethylphenyl (Mes)), which were characterized by IR, electronic, 1H and 19F NMR spectroscopy and X-ray crystallographic analyses.Complex 1a (R = Xyl) crystallizes in the triclinic form, space group P1, with a = 13.431(5) Angstroem, b = 15.548(7) Angstroem, c = 12.616(5) Angstroem, α = 111.74(3) deg, β = 92.80(3) deg, γ = 101.80(3) deg and Z = 1 (R = 0.060 and R_w = 0.054 for 2818 independent reflections with I>3?(I)).Complex 2b (R = Mes) crystallizes in the triclinic form, space group P1, with a = 14.317(4) Angstroem, b = 16.16(1) Angstroem, c = 8.968(8) Angstroem, α = 100.31(4) deg, β = 97.54(2) deg, γ = 91.69(4) deg and Z = 2 (R = 0.059 and R_w = 0.059 for 2225 independent reflections with I>3?(I)).Complex 1 consists of two molybdenum atoms bridged linearly by an oxygen atom.Each molybdenum atom is octahedrally coordinated by five isocyanides and an oxygen atom.Two equatorial planes, Mo(RNC)4, mutually adopt an eclipsed form.The Mo-O bond length is 1.876(2) Angstroem and the Mo-O-Mo angle is constrained to 180 deg.Complex 2 has a distorted octahedral geometry, in which molybdenum atom is occupied by four isocyanides, O and F atoms.Keywords: Molybdenum; Oxo-bridged dinuclear complexes; X-ray diffraction; Isocyanide; EHMO