Photochemical ligand dissociation, electron transfer, and metal-metal bond cleavage of phosphine-substituted cobalt carbonyl complexes

Article abstract of DOI:10.1021/om00084a013

The major photochemical reactions of [Co(CO)₃L₂][Co(CO)₄] are initiated by photolysis of the cation Co(CO)₃L₂⁺. Upon photolysis Co(CO)₃L₂⁺ loses a ligand, either CO or L (L = tributylphosphine), to give Co(CO)₂L₂⁺ and Co(CO)₃L⁺ which will react with Co(CO)₄^- to give Co₂(CO)₆L₂ and Co₂(CO)₇L, with excess L to give Co(CO)₂L₃⁺ and Co(CO)₃L₂⁺, and with H₂ to give HCo(CO)₂L₂ and HCo(CO)₃L, respectively. The neutral complex Co₂(CO)₆L₂ is photostable in the absence of phosphine. With an excess of L it undergoes either photosubstitution to Co₂(CO)₅L₃ and Co₂(CO)₄L₄ or disproportionation to [Co(CO)₂L₃][Co(CO)₄] (major) and [Co(CO)₃L₂][Co(CO)₃L], depending on the nature of the solvent (hexane or methanol, respectively). Electron-transfer and radical reactions are responsible for the observed products.