Co-ordinatively unsaturated diene complexes of tungsten(II) and their reactions with nucleophilesto give six- and seven-co-ordinate derivatives

Jack L. Davidson, Guiseppe Vasapollo

Research output: Contribution to journalArticle

Abstract

[{WBr2(CO)4}2] reacts with the 'dienes' (L') cyclo-octa-1,5-diene (cod), cyclo-octatetraene (cot), and norbornadiene (bicyclo[2.2.1] hepta-2,5-diene, nbd) to give co-ordinatively unsaturated complexes [WBr2(CO)2L']. These react with Lewis bases L [= CNBut, PMe2Ph, or P(OMe)3] (1:1 molar ratio) to give co-ordinatively unsaturated diene complexes [WBr2(CO)LL'] via intermediate 1:1 adducts [WBr2(CO)2LL'] isolated in the case of the norbornadiene complexes. With a 3:1 molar ratio of ligand:metal, displacement of cod or cot occurs to give [WBr2(CO)2L3] [L = P(OMe)3, PMe2Ph, or CNBut], while a 4:1 molar ratio (L = CNBut) gives [WBr2(CO)(CNBut)4]. In contrast, [WBr2(CO)2(nbd)] forms monocarbonyl diene complexes [WBr2(CO) L2(nbd)] [L = P(OMe)3 or PMe2Ph, L2 = 2,2'-bipyridyl]. Proton and 31P n.m.r. studies of [WBr2(CO)2L3] [L = P(OMe)3 or PMe2Ph] reveal the presence of two isomeric forms which exhibit dynamic stereochemistry at ambient temperature while the static form of one isomer could be detected at lower temperatures.

Original languageEnglish
Pages (from-to)2231-2238
Number of pages8
JournalJournal of the Chemical Society, Dalton Transactions
Issue number11
DOIs
Publication statusPublished - 1985

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