The photoinsertion of tin(II) chloride into the metal–metal bond of hexacarbonylbis(tri-n-butylphosphine)dicobalt

Abstract

. Can. J. Chem. 55, 2279Chem. 55, (1977. The photochemical insertion reaction of SnCI, into the metal-metal bond of [P(n-C4Hg),-C O ( C O )~]~ has been studied in THF at 23.0°C at the irradiating wavelengths 365 nm, 436 nm, and 546 nm. At 365 nm, the quantum yield for the reaction increases with increasing concentration of SnCI, and approaches a limiting value of 1.0. At 436 nm, however, the quantum yield increases above 1.0 and at 546 nm, quantum yields as high as 6 were measured. The uv-visible absorption spectrum of [P(n-C,H,),Co(CO),], shows an intense band at 372 nm and a broad shoulder at about 440 nm. A simple mechanism is proposed to operate on irradiation at 365 nm due to absorption by the intense band, but a more complicated chain mechanism is suggested to operate at 546 nm as a result of absorption by the lower energy shoulder band. It appears that both mechanisms operate on irradiation at 436 nm due to the overlap of the two absorption bands at this wavelength. Introduction the basis of the homolytic fission of the M-M There has been a recent surge of interest in the bond (I), or in solvents of high donicity, on the mechanisms of the photochemical reactions of heterolytic fission of this bond (2). Studies have transition metal carbonyl complexes containing shown that the lowest excited states of the M-M metal-metal (M-M) bonds (1-7). The photo-bonded species produced on absorption of radiachemistry of these complexes can be explained on tion result from an electronic transition which weakens the M-M bond, either by an electron