Photochemical studies as a function of solvent viscosity. A new photochemical pathway in the reaction of (η5-C5H4Me)2Mo2(CO)6 with CCl4

Abstract

This paper reports the results of a study that used systematic changes in the solvent viscosity to probe the photochemical reactivity of the Cp′₂Mo₂(CO)₆ (Cp′ = η⁵-C₅H₄CH₃) molecule. The quantum yields for photolysis of Cp′₂Mo₂(CO)₆ in the presence of CCl₄ were studied as a function of solvent viscosity. The quantum yields did not decrease to zero with increasing solvent viscosity but rather leveled off at a constant, non-zero value. This result cannot be explained by any of the previously reported radical or Mo–CO dissociation photochemical pathways for this molecule, and therefore an additional photochemical pathway is suggested to be operating in the reaction. The new pathway may involve a reactive isomer of Cp′₂Mo₂(CO)₆ or possibly electron transfer between the excited state of Cp′₂Mo₂(CO)₆ and CCl₄.