Reactions of monocyclopentadienyl complexes of molybdenum and tungsten with derivatives of phenols and pentafluorobenzeneselenol

Jack L. Davidson, Birgit Holz, Pascal C. Leverd, W. Edward Lindsell, Nigel J. Simpson

Research output: Contribution to journalArticle

Abstract

Reactions of [WI3(CO)2(Cp)] (cp = ?5-C5H5) with thallium salts Tl(OR) (R = aryl) in tetrahydrofuran did not produce simple substitution products but afforded reduced species [W(OC6F5)(CO)3(Cp)] 2, oxidised species [W(OC6H4Me-p)6] or the thallium tritungsten derivative [Tl{W(CO)3(cp)}3] (when R = C6H3Pri22,6). Complex 2 is a rare example of a derivative of type [WX(CO)3(Cp)] in which X is an oxygen-bonded ligand. Photolysis of [{Mo(CO)3(cp)}2] with Se2(C6F5)2 in toluene yields [Mo(SeC6F5)(CO)3(Cp)] 8a, and the thermal reaction of [MoCl(CO)3(Cp)] with two equivalents of Tl(SeC6F5) in diethyl ether gives the thallium complex Tl[Mo(SeC6F5)2(CO)2(Cp)] 9, via complex 8a isolated as a by-product. Reaction of [WBr3(CO)2(Cp)] with three equivalents of Tl(SeC6F5) produces [W(SeC6F5)3(CO)(Cp)] 12, with [W(SeC6F5)(CO)3(Cp)] 8b as a by-product, and further reaction of 12 with Tl(SeC6F5) forms [TlW(SeC6F5)4(Cp)] 11b. Variable-temperature 19F NMR studies show that complexes 9, 11b and 12 are fluxional and show hindered motion of the C6F5 rings. In complexes 9 and 11b, thallium(I) is co-ordinated by the selenolate ligands of the organometallic anion and coupling between 103/105Tl and 19F ortho-fluorine nuclei is observed in the 19FNMR spectra. Complex 12 comprises two conformers in equilibrium which are detected by NMR studies at low temperature. Comparisons are drawn between properties of the new selenium complexes and related sulfur derivatives.

Original languageEnglish
Pages (from-to)3527-3532
Number of pages6
JournalJournal of the Chemical Society, Dalton Transactions
Issue number24
DOIs
Publication statusPublished - 1994

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