Photochemistry of (η-benzene)tricarbonylchromium, tricarbonyl-(η-cyclopentadienyl)manganese, and (η-cyclobutadiene)- and (tris-methylenemethane)-tricarbonyliron in frozen gas matrices at 12 K. Infrared spectroscopic evidence for dicarbonylmetal and dicarbonyl-(dinitrogen)metai complexes

Abstract

Infrared evidence is presented for the formation of co-ordinatively unsaturated species [ML(CO)₂][ML = Cr-(η-C₆H₆), Mn(η-C₅H₅), or Fe(η-C₄H₄), or Fe{C(CH₂)H₃}] on the u.v. photolysis of [ML(CO)₃] complexes in argon and methane matrices, and dinitrogen complexes [ML(CO)₂(N₂)] in nitrogen matrices at 12 K. The primary photolysis step is readily reversed by visible light for [ML(CO)2] species of Cr and Fe, but not for Mn. The results are discussed in relation to the postulate of co-ordinatively unsaturated species as intermediates in the solution-phase substitution reactions.