Mixed-metal cluster chemistry. 26 [1]. Proclivity for "all-terminal" or "plane-of-bridging-carbonyls" ligand disposition in tungsten-triiridium clusters

Alistair J. Usher, Gulliver T. Dalton, Nigel T. Lucas, Susan M. Waterman, Simon Petrie, Robert Stranger, Mark G. Humphrey*, Anthony C. Willis

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    7 Citations (Scopus)


    Reaction of WH(CO)3(η-C5Me5) with IrCl(CO)2(4-H2NC6H4Me) affords WIr3(μ-CO)3(CO)8 (η-C5Me5) in low yield. A structural study reveals a WIr2-centred plane of bridging carbonyls, in contrast to the crystal structure of WIr3(CO)11 (η-C5H5) (all-terminal carbonyl distribution). DFT calculations reveal an increasing proclivity to adopt an all-terminal CO disposition for clusters MIr3(CO)11 (η-C5H5) in the gas phase on proceeding from M=Cr to Mo and then W, consistent with structural studies in the solid state for which the tungsten-containing cluster is the only all-terminal example. Increasing electron donation from the ligands in the tungsten system (either from phosphine substitution or cyclopentadienyl permethylation) suffices to impose a plane of bridging carbonyls in the ground state structure. 13C NMR fluxionality studies reveal that CO exchange mechanism(s) for WIr3(CO)11 (η-C5H5) and the related tetrahedral cluster W2Ir2(CO)10(η-C5 H5)2 are very fast and involve all carbonyls on the clusters. DFT calculations on MIr3(CO)11 (η-C5H5) (M=Cr, Mo) substantiate a ' merry-go-round' mechanism for carbonyl scrambling in these systems, a result which is consistent with the scrambling behaviour seen in the NMR fluxionality studies on the W-containing congener.

    Original languageEnglish
    Pages (from-to)50-57
    Number of pages8
    JournalJournal of Organometallic Chemistry
    Issue number1
    Publication statusPublished - 5 Jan 2004


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