Photochemistry of tricarbonyl(η4-cyclo-octatetraene)iron in a methane matrix at 12 K. Infrared spectroscopic evidence for photoisomerisation and carbon monoxide ejection reactions

Abstract

Fourier-transform infrared spectroscopic evidence, including ¹³CO labelling and energy-factored CO force-field fitting, is presented to show that photolysis of [Fe(‘tub’-η⁴-C₈H₈)(CO)₃] in a CH₄ matrix at 12 K leads to the formation of a [Fe(‘chair’-η⁴-C₈H₈)(CO)₃] species via the [Fe(η²-C₈H₈)(CO)₃] intermediate. An additional photoproduct is the co-ordinatively unsaturated species [Fe(η⁴-C₈H₈)(CO)₂] formed by photoelimination of a CO ligand. The results are related to the fluxional behaviour of [Fe(η⁴-C₈H₈)(CO)₃] in solution.