Photochemical reduction of CpW(CO)3CH3 (Cp = η5-C5H5) to CpW(CO)3 -; An isolobal analogy to the disproportionation of Cp2Mo2(CO)6

Alan S Goldman, David R. Tyler

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Irradiation (λ > 380 nm) of CpW(CO)3Me in inert solvents in the presence of PPh3 gives [PPh3CH3 +][CpW(CO)3 -] as well as the substitution product CpW(CO)2(PPh3)Me (φdisappearance CpW(CO)3Me = 0-45 ± 0.005, φappearance CpW(CO)3- = 0.04 ± 0.01). The mechanism of CpW(CO)3 - formation was studied. Experiments suggest that CpW(CO)2(PPh3)Me may be an intermediate in the reaction but direct reductive elimination of PPh3Me+ from this species or from CpW(CO)(PPh3)2Me was ruled out. Experiments using PTol3 demonstrated that PAr3Me+ (Ar = aryl) is formed from exogenous, not coordinated, phosphine. The mechanism proposed for the reduction of CpW(CO)3Me involves the intermediate formation of phosphoranyl radicals, -PPh3Me, formed by addition of Me radicals (from W-CH3 homolysis) to PPh3. Phosphoranyl reduction of a variety of metal species which are present in solution is shown to lead to CpW(CO)3 -. The proposed mechanism is isolobal with a mechanism we proposed for the photochemical disproportionation of metal-metal bonded dimers (e.g., Cp2Mo2(CO)6) involving 19-valence-electron intermediates.

Original languageEnglish
Pages (from-to)89-94
Number of pages6
JournalJournal of the American Chemical Society
Issue number1
Publication statusPublished - 1986


ASJC Scopus subject areas

  • Chemistry(all)

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