Photochemical reactions of Group 6 metal carbonyls with alkenes

The aim of this survey article is to bring into focus intriguing areas of Group 6 metal alkene coordination chemistry that have not been extensively surveyed to date. Photochemical reactions of Group 6 transition metal carbonyls with alkenes and the formation of alkene carbonyl complexes of the type: [M(CO)5(η2-alkene)], [M(CO)4(η2-alkene)2], and [M(CO)3(η2-alkene)3] are the point of departure. The crystal structures of these compounds together with their spectroscopic characteristics in solution are discussed. An overview of the reactivity and catalytic activity of these compounds is also given. Special attention is given to catalytic reactions that lead to the formation of new carbon-carbon bonds, such as metathesis, ring-opening metathesis polymerization of cyclic olefins (ROMP), and the addition of haloalkanes to the double bond of olefin.