J. L. Davidson, Michael J. Green, F. Stone
1979
Citations
0
Influential Citations
16
Citations
Journal
Journal of The Chemical Society-dalton Transactions
Abstract
Reaction of [Ni(CO)4] with hexafluorobut-2-yne gives initially [Ni(CO)2(η2-CF3C2CF3)], which decomposes to afford the cluster complex [Ni4(CO)4{µ3-(η2-CF3C2CF3)}3], the structure of which has been established by single-crystal X-ray diffraction studies. It crystallises in the monoclinic space group P21/m, with two molecules in a unit cell of dimensions a= 8.506(2), b= 16.055(12), c= 9.011(4)A, and β= 100.52(3)°. The structure has been elucidated via analysis of 1 033 significant reflections, and refined to R 0.13, R′ 0.165. The molecule has essentially C3v symmetry consisting of a trigonal pyramid of nickel atoms [Ni(basal)–Ni(basal) 2.670, Ni(basal)–Ni(apical) 2.382 A] each carrying a terminally bonded carbonyl group, and three face-bridging, µ3(η2-⊥), acetylenic ligands. Reactions of the tetranuclear nickel cluster with 1,2-bis(diphenylphosphino)ethane (dppe) or ButNC gives the mononuclear complexes [NiL2(η2-CF3C2CF3)](L2= dppe, L = CNBut). In contrast, cyclo-octatetraene affords [Ni3(CO)3{µ3-(η2-CF3C2CF3)}{µ3-(η2-C8H8)}], the structure of which has also been determined by X-ray crystallography. Crystals are monoclinic, space group P21/n, with four molecules in a unit cell of dimensions a= 9.5915(19), b= 11.994(3), c= 14.876(4)A, and β= 99.57(2)°. Least-squares refinement using 2 114 reflections has converged at R 0.040, R′ 0.048. An isosceles triangle of nickel atoms [Ni(basal)–Ni(basal) 2.702, Ni(basal)–Ni(apical) 2.457 A], each carrying a terminal carbonyl ligand, is sandwiched between a planar cyclo-octatetraene ring and a face-bonding acetylene molecule whose orientation with respect to the metal triangle is complementary, µ3(η2-∥), to that observed in the tetranuclear complex. Evidence is presented for regarding the C8H8 ligand as a co-ordinated 6-π-electron [C8H8]2+ species.