Preparation and characterisation of dicarboxylatobis(η-cyclopentadienyl)-tungsten(IV) complexes: a novel and convenient synthesis from [W(η-C5H5)2H2] using molecular oxygen as a hydrogen acceptor
Abstract
The reactions of [W(η-C5H5)2H2](1) with carboxylic acids under various conditions were investigated. At room temperature in the dark, the reaction afforded reversibly [W(η-C5H5)2H3]+(3), whereas the same reaction under irradiation by light yielded [W(η-C5H5)2(OCOR)2](2)[R = Me, Et, CH2C(Me), or H] in small amounts. Addition of 1 equivalent of O2 to the reaction system significantly improved the yields of (2) producing water as a by-product. Complexes (2) containing unidentate carboxylate were characterised by i.r. and 1H n.m.r. spectra and by elemental analyses. The formation of the species [W(η-C5H5)2(OCOMe)(H2O)]+ was proposed on the basis of the 1H n.m.r. measurements of (2; R = Me) in CD3CO2D containing D2O.