Photochemical or electrochemical bond breaking - exploring the chemistry of (μ-alkyne)Co(CO) complexes using time-resolved infrared spectroscopy, spectro-electrochemical and density functional methods

The photochemistry of (μ 2 -CRCR′)Co 2 (CO) 6 complexes (R = pyrenyl, R′ = H; R = pyrenyl, R′ = ferrocenyl; R = ferrocenyl, R = H) was investigated by ps-time-resolved infrared spectroscopy at room temperature in dichloromethane solution. The main focus of these studies was to determine the primary photoprocess relevant to the light assisted Pauson-Khand reaction. These studies were supported by spectro-electrochemical investigations and density functional calculations which suggest that the primary process to initiate the Pauson-Khand reaction involves a homolytic cleavage of the Co-Co bond forming a high-spin diradical species and not CO-loss as previously thought. The photoassisted Pauson-Khand reaction involves the formation of a high-spin diradical species and not CO loss as previously thought.