Photochemical studies on η 5-cyclopentadienyl(triphenylphosphine)nickelalkyl and -aryl compounds

Abstract

Photo-induced degradation studies of a series of organonickel complexes of the type (η 5-C 5H 5)(PPh 3)Ni(R) (R = CH 3, C 2H 5, C 6H 5 and C 6H 4CH 3- p) as well as certain deuterated analogs have been undertaken. Photolysis of the methyl compounds in benzene as well as benzene- d 6 gives methane as the major gaseous product, the photogenerated methyl group abstracting hydrogen from either the cyclopentadienyl ring, from the solvent, or from another methyl group. The photo-induced dealkylation of the ethyl compound gives both ethylene and ethane, and is explained by β-hydride elimination followed by subsequent reaction of the hydrido intermediate with additional ethyl compound. The photolysis of the phenyl and p-tolyl complexes in benzene solution leads to biaryl formation, both from the coupling of two coordinated aryl groups as well as interactions with the solvent. Triphenylphosphine is a product in all of these photo-decomposition studies.