Reactions of molybdenum and tungsten η2-C,C-vinyl complexes [Mη3-C(CF3)C(CF3)SR(CF3CCCF3)(η5-C5H5)] with alkynes leading to novel metallacycles

L. Carlton, Naz M. Agh-Atabay, Jack L. Davidson

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The reactions of [M?3-C(CF3)C(CF3)SR(CF3C=CCF3)(?5-C5H5)](M = Mo, R = iPr; M = W, R = Me, iPr, tBu) with alkynes R'C=CR?, (R' = R? = Me, Et, Ph; R' = Ph, R? = Me) gives isomeric ?2-vinyl [M?3-C(CF3)C(CF3)C(R?)=C(R')(SR)(CF3C=CCF3)(?5-C5H5)] and/or ?4-butadienyl complexes [M?4-C(CF3)C(CF3)=C(R?)C(R')(SR)(CF3C=CCF3)(?5-C5H5)] (not all cases) apparently as a result of insertion of the incoming alkyne into the CS bond of the ?3-C(CF3)C(CF3)SR ligand. Thermolysis of [W?3-C(CF3)C(CF3)C(Me)=C(Ph)SiPr(CF3C=CCF3)(?5-C5H5)] in hexane at 55°C gives [WSiPr?5-C(CF3)C(CF3)C(CF3)C(CF3)C(Me)C(Ph)(?5-C5H5)]. In contrast thermolysis of [Mo?3-C(CF3)C(CF3)C(Me)=C(Me)SiPr(CF3C=CCF3)(?5-C5H5)] in hexane at 70°C gives [Mo?4-C(Me)C(Me)=C(CF3)C(CF3)(H)(CF3C=CCF3)(?5-C5H5)] via the intermediate [Mo?4-C(CF3)C(CF3)=C(Me)C(Me)SiPr(CF3C=CCF3)(?5-C5H5)]. Fluxional behaviour in complexes [M?3-C(CF3)C(CF3)C(R?)=C(R')(SR)(CF3C=CCF3)(?5-C5H5)] has been studied by variable temperature 19F NMR spectroscopy and two processes detected. The first involves rapid exchange between two isomeric forms and is ascribed to inversion at either the sulphur or the ß-carbon of the C(CF3)C(CF3)C(R?)=C(R')SR ligand. The second appears to involve restricted rotation of the CF3 attached to the ß-carbon. © 1991.

Original languageEnglish
Pages (from-to)205-221
Number of pages17
JournalJournal of Organometallic Chemistry
Issue number1-3
Publication statusPublished - 7 Aug 1991


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