Reactions of alkynes with molybdenum and tungsten bis(alkyne) complexes

Naz M. Agh-Atabay, Jack L. Davidson, Uta Dullweber, Graeme Douglas, Kenneth W. Muir

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Abstract

The reaction of [Mo(SC6F5)(CF3C=CCF3) 2(?5-C5H5)] 1a with MeO2CC=CCO2Me at -30°C gave a butadienyl complex [Mo{?4-C(CF3)=C(CF3)C(CO 2Me)C(CO2Me)(SC6F5)}(CF 3C=CCF3)(?5-C5H 5)] which has been shown by X-ray analysis to contain an (?5-C5H5)Mo(?2-CF 3C=CCF3) unit attached to the C(CF3)=C(CF3)C(CO2Me)=C(CO 2-Me)SC6F5 butadienyl ligand through a CO2Me carbonyl oxygen atom and Ca, C?, and Cd of the butadiene chain. The structure and bonding in this complex and in related butadienyl and co-ordinated ester complexes are compared. It rearranges above ca. -20°C to give isomeric complexes [Mo{?5-C(CF3)C(CF3)C(CF 3)C(CF3)C(CO2Me)=C(CO2-Me)SC6F 5}(?5-C5H5)] in which linkage of the butadienyl and co-ordinated alkynes has occurred to give ?5 or ?6 tris-(alkyne) ligands. The complex [W(SC6H4Me-4)(CF3C=CCF3) 2(?5-C5H5)] 1b and MeO2CC=CCO2Me reacted at -20 to -15°C to give a butadienyl complex [W{?5-C(CF3)=C(CF3)C(CO 2Me)C(CO2Me)(SC6H4Me-4)}(CF 3-C=CCF3)(?5-C5H 5)] similar to the molybdenum complex but containing a co-ordinated thiolate sulfur instead of a carbomethoxy oxygen bonded to the metal. It isomerises above ca. -10°C to give the sixteen electron complex [W(SC6H4Me-4) {?4-C(CF3)=C(CF3)C(CO 2Me)=C(CO2Me)C(CF3)=C(CF3)} (?5-C5H5)] containing a novel seven-membered metallacyclic ring. In contrast 1b and non-activated alkynes RC=CR' (R = R' = Me; R = Me or Ph, R' = Ph) reacted to give the ?3- and ?4- butadienyl complexes [W{?3-C(CF3)C(CF3)C(R)=C(R')SC 6H4Me-4}-(CF3C=CCF 3)(?5-C5H5)] and [W{?4-C(CF3)C(CF3)=C(Me)C(Me)SC 6H4Me-4}(CF3C=CCF3)(? 5-C5H5)] with no evidence for alkyne trimerisation. The pathways which lead to different alkyne oligomerisation patterns are discussed. © The Royal Society of Chemistry 1999.

Original languageEnglish
Pages (from-to)3883-3892
Number of pages10
JournalJournal of the Chemical Society, Dalton Transactions
Issue number21
Publication statusPublished - 7 Nov 1999

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    Agh-Atabay, N. M., Davidson, J. L., Dullweber, U., Douglas, G., & Muir, K. W. (1999). Reactions of alkynes with molybdenum and tungsten bis(alkyne) complexes. Journal of the Chemical Society, Dalton Transactions, (21), 3883-3892.