MATRIX-ISOLATION AND AB-INITIO MOLECULAR-ORBITAL STUDY OF FLUOROCYCLOPROPENONE AND FLUORO(KETENYL)CARBENE

Irradiation of fluoromaleic anhydride (4) under matrix isolation conditions in argon produces fluoro(ketenyl)carbene (6s) and fluorocyclopropenone (7) as primary photoproducts. Fluoro(ketenyl)carbene is quickly converted to fluoroacetylene and carbon monoxide under the irradiation conditions while fluorocyclopropenone is slowly converted to the same products. The photochemical destruction of fluorocyclopropenone is greatly accelerated by using shorter wavelength irradiation. Gas phase irradiation of fluoromaleic anhydride at room temperature leads only to difluoroacetylene as does treatment of the anhydride under flash vacuum pyrolysis conditions. Ab initio calculations are reported for fluoropropadienone, fluoro(ketenyl)carbene, and fluorocyclopropenone, and the results are compared with experiment.