Syntheses and reactions of η2-vinyl complexes of molybdenum and tungsten [M(SC6F5){η2-C(CF3)C(CF 3)(PR3)}-(CF3C≡CCF3)(cp)] and [mo{η3-C(CF3)C(CF3)(SPr i)}-(CF3C≡CCF3)(cp)] (cp = η-C5H5)

N. M. Agh-Atabay, Laureano J. Canoira, Laurence Carlton, Jack L. Davidson

Research output: Contribution to journalArticle

Abstract

Reactions of bis(hexafluorobut-2-yne) complexes [M(SC6F5)(CF3C=CCF3) 2(cp)] (M = Mo, 1a; or W, 1b with tertiary phosphines and phosphites (L) give ?2-vinyl complexes [M(SC6F5){?2-C(CF3)C(CF 3)L}-(CF3C=CCF3)(cp)] 3 [(M = Mo or W; L = PEt3, PMe2Ph or PMePh2; M = W, L = P(OMe)3] as a result of attack at an alkyne carbon. Several isomeric forms of complexes 3 have been detected by NMR spectroscopy. Reactions of phosphines with the ?2-C,C vinyl complex [Mo{?3-C(CF3)C(CF3)SPri}(CF 3C=CCF3)(cp)] 2 in contrast give ?4-butadienyl derivatives [Mo{C(CF3)=C(CF3)C(CF3)=C(CF 3)-(SPri)}L(cp)] 4 (L = PEt3, PMe2Ph, or MeC=CPPH2) apparently as a result of insertion of the alkyne into the M=C bond of the ?2-C,C vinyl. A similar complex 4 is obtained when 3 (M = Mo, L = PMe2Ph) is allowed to isomerise in diethyl ether at room temperature. In contrast 3 (M = Mo, L = PMe2Ph) isomerises in refluxing hexane to the tetrakis(trifluoromethyl)cyclobutadiene complex [Mo(SC6F5)-(PMe2Ph){?4-C 4(CF3)4}(cp)] 9. An alternative isomerisation process is observed in diethyl ether at 18°C where the product [MoF{?3-C(CF2)C(CF3)=C(CF 3)C(CF3)(SC6F5)}L(cp)] 8 (L = PEt3 or PMe2Ph) results from linking of two CF3C=CCF3 ligands and a C6F5S group and fluorine transfer from a CF3 to the metal. Fluxional behaviour in complexes 3,8 and 9 has been studied by 19F NMR spectroscopy.

Original languageEnglish
Pages (from-to)1175-1182
Number of pages8
JournalJournal of the Chemical Society, Dalton Transactions
Issue number5
DOIs
Publication statusPublished - 1991

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