Photo-reversible isomerisation of trans- to cis-[W(CO)4(η2-alkene)2] complexes in low-temperature matrices

Article abstract of DOI:10.1016/S0022-328X(96)06725-3

Reversible isomerisation of trans- to cis-[W(CO)₄(η²-alkene)₂] complexes has been induced in argon matrices at low temperatures under the action of selective irradiation. UV photolysis (λ ≈ 313nm) of trans-[W(CO)₄(η²-alkene)₂] (alkene = cyclopentene or 1-pentene) in an argon matrix at 16 K results in formation of the cis isomer as the primary photoprocess. The isomerisation is reversed under the action of visible light (λ ≈ 445nm). Species such as [W(CO)₄(alkene)(Ar)] are also formed in small concentrations. Experiments involving annealing, selective photolysis and the use of CO- or alkene-doped matrices have been performed to investigate the mechanism of the photo-isomerisation process. These studies suggest a dissociative mechanism via expulsion of the alkene ligand.