Evidence for cobalt-cobalt bond homolysis and wavelength-dependent CO loss in (μ2-alkyne)Co2(CO)6 complexes.

Time-resolved infrared spectroscopy was used to probe the photochemistry of three (μ(2)-alkyne)Co(2)(CO)(6) complexes. The data indicate the formation of a triplet diradical species, with lifetimes in the range 38-71 ps. Theoretical calculations support these experimental findings. No evidence for the CO loss species, (μ(2)-alkyne)Co(2)(CO)(5), was observed, and this is rationalized by the low quantum yield for this process at the excitation wavelengths used.