Rhenium-carbon bond photochemical cleavage

An alternative procedure involves the photochemical cleavage of the rhenium-rhenium bond in dirhenium decacarbonyl in the presence of a chlorocarbon solvent.21,22 This method suffers from contamination by the tetracarbonylchloro-rhenium dimer, which forms in large quantities during photolysis.21,22 To prevent formation of dimer, the photolysis is performed under an atmosphere of carbon monoxide. The yield of ReCl(CO)5 is essentially quantitative using this procedure. 

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