Synthesis and characterization of dinuclear metal σ-acetylides and mononuclear metal σ-allenylidenes

Michael C.B. Colbert, Jack Lewis, Nicholas J. Long, Paul R. Raithby, Muhammad Younus, Andrew J.P. White, David J. Williams, Nicholas N. Payne, Lesley Yellowlees, David Beljonne, Nazia Chawdhury, Richard H. Friend

Research output: Contribution to journalArticle

120 Citations (Scopus)

Abstract

A series of dinuclear metal σ-acetylides of the type trans-[Cl(P-P)2MC≡CRC≡CM(P-P)2Cl] (M = Fe, Ru, Os; P-P = 1,2-bis(diphenylphosphino)methane (dppm), 1,2-bis(diethylphosphino)ethane (depe), 1,2-bis(dimethylphosphino)ethane (dmpe); R = 1,4-benzenediyl, 1,3-benzenediyl, 2,5-xylenediyl, 2,5-pyridinediyl, 2,5-thiophenediyl) have been formed. Electrochemistry of these complexes shows that there is a metal-metal interaction which is dependent upon the metal and the π-conjugated bridging ligand. Coulometry and optical absorbance spectroscopic studies show the presence of mixed-valence oxidized species which possess a delocalized allenylidene structure and can be classified as Robin and Day "class II" mixed-valence species. Theoretical calculations have been carried out to optimize the geometric structure of the bridging acetylide ligand and indicate that the conjugated system undergoes a structural change upon oxidation to give a quinoid-like geometry. Two mononuclear metal-allenylidene complexes, [Cl(dppm)2M=C=C=CHPh][PF6] (10, M = Ru; 11, M = Os), have also been synthesized and an X-ray crystal structure determination on 10 undertaken. This shows a distorted-octahedral coordination about ruthenium and distinct double-bond character extending along the M-C-C-C chain, which is essentially linear. Structural and spectroscopic details on the metal allenylidenes have been compared to those of the mixed-valence oxidized dinuclear metal acetylides and show that the latter exist in a delocalized allenylidene form.

Original languageEnglish
Pages (from-to)3034-3043
Number of pages10
JournalOrganometallics
Volume17
Issue number14
DOIs
Publication statusPublished - 6 Jul 1998

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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