Arene–molybdenum chemistry: reactions of di-µ-chloro-bis[(η-allyl)-(η-arene)molybdenum] with cyclic olefins

Abstract

The violet solutions formed form (AlEtCl₂)₂ and the compounds [{Mo(η-C₃H₅)(η-arene)Cl}₂](arene = C₆H₆, C₆H₅Me, or C₆H₃Me₃-1,3,5) react with norbornadiene (nbd), cyclo-octa-1,3,5,7-tetraene(cot), or cyclohepta-1,3,5-triene (cht), and the corresponding cations [Mo(η-C₃H₅)(η-arene)(η-olefin)]⁺ have been is olated from the hydrolysed reaction mixtures. Prolonged reaction with cht yields the cycloheptatrienly sandwich compounds [Mo(η-C₇H₇)(η-arene)][PF₆]. The comound [Mo(η-C₃H₅)(η-C₆H₆)(cht)][PF₆] undergoes deprotonation on an alumina column to the neutral compound [Mo(η-C₃H₅)(η-C₆H₆)(η³-C₇H₇)]. The violet solution reacts with cyclopentene and hydrolysis of the product in the presence of lithium chloride or alkaline sodium dithionite gives [Mo(η-C₅H₅)(η-C₆H₆)Cl] or paramagnetic [Mo(η-C₅H₅)(η-C₆H₆)] respectively; with cyclohexene the 17-electron cation [Mo(η-C₆H₆)₂]⁺ is formed in high yield.