Formation of tetra- and tri-nuclear nickel acetylene complexes; crystal and molecular structures of tris-μ3-(η2-hexafluorobut- 2-yne)-tetrakis-(carbonylnickel) and tricarbonyl-μ3-(η-cyclo- octatetraene)-μ3-(η2-hexafluorobut-2-yne) -triangulo-trinickel with evidence for a nickel-stabilised cyclo-octatetraenyl dication

Jack L. Davidson, Michael Green, F. Gordon A. Stone, Alan J. Welch

Research output: Contribution to journalArticle

Abstract

Reaction of [Ni(CO)4] with hexafluorobut-2-yne gives initially [Ni(CO)22-CF3C2CF 3)], which decomposes to afford the cluster complex [Ni 4(CO)43-(η2-CF 3C2CF3)}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) Å, 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 Å] each carrying a terminally bonded carbonyl group, and three face-bridging, μ32-box drawings light up and horizontal), acetylenic ligands. Reactions of the tetranuclear nickel cluster with 1,2-bis(diphenylphosphino)ethane (dppe) or ButNC gives the mononuclear complexes [NiL22-CF3C 2CF3)] (L2 = dppe, L = CNBut). In contrast, cyclo-octatetraene affords [Ni3(CO) 33-(η2-CF3C 2CF3)}{μ3-(η2-C 8H8)}], 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) Å, 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 Å], 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, μ32-∥), 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.

Original languageEnglish
Pages (from-to)506-514
Number of pages9
JournalJournal of the Chemical Society, Dalton Transactions
Issue number3
DOIs
Publication statusPublished - 1979

ASJC Scopus subject areas

  • Chemistry(all)

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