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

被引:125
作者
Colbert, MCB
Lewis, J
Long, NJ
Raithby, PR
Younus, M
White, AJP
Williams, DJ
Payne, NN
Yellowlees, L
Beljonne, D
Chawdhury, N
Friend, RH
机构
[1] Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England
[2] Univ London Imperial Coll Sci Technol & Med, Dept Chem, London SW7 2AY, England
[3] Univ Edinburgh, Dept Chem, Edinburgh EH9 3JJ, Midlothian, Scotland
[4] Univ Mons, B-7000 Mons, Belgium
[5] Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England
关键词
D O I
10.1021/om970130p
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
A series of dinuclear metal sigma-acetylides of type trans-[Cl(P-P)(2)MC=CRC=CM(P-P)(2)Cl] (M = Fe, Ru, Os; P-P = 1,2-bis(diphenylphosphino)methane (dppm), 1,2-bis(diethyl-phosphino)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 pi-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)(2)M=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.
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页码:3034 / 3043
页数:10
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