Transition-metal chemistry of octafluorocyclooctatetraene. Synthesis and X-ray structure of a novel five-coordinate cis-dialkyl nickel complex

Article abstract of DOI:10.1021/om00136a038

Reaction of Ni(COD)₂ with 2 equiv of the phosphines PMe₃ or PPhMe₂ (L) in the presence of octafluorocyclooctatetraene (OFCOT) affords the first examples of Ni(0) compounds containing two coordinated fluoroolefins [Ni(1,2,5,6-η-OFCOT)L₂] (1); use of exactly 2 equiv of t-BuNC instead of a phosphine yields the metallacyclic complex [Ni(C₈F₈)(t-BuNC)₂] (C₈F₈ = perfluorobicyclo[3.3.0]octadienediyl) (2) which does not undergo reductive elimination in the presence of exogenous ligands to give perfluorosemibullvalene (3) but instead forms the first stable examples of five-coordinate cis-dialkyl complexes of nickel [Ni(C₈F₈)(t-BuNC)₂L] (4) (L = t-BuNC, PMe3, PPh₃), one of which, 4b (L = PMe₃), has been characterized by a single-crystal X-ray diffraction study at -110°C.