Near-UV Water Splitting by Cu, Ni, and Co Complexes in the Gas Phase

(2,2′-Bipyridine)M═O+ ions (M = Cu, Ni, Co) were generated by collision-induced dissociation and near-UV photodissociation of readily available [(2,2′-bipyridine)MII(NO3)]+ ions in the gas phase, and their structure was confirmed by ion–molecule reactions combined with isotope labeling. Upon storage in a quadrupole ion trap, the (2,2′-bipyridine)M═O+ ions spontaneously added water, and the formed [(2,2′-bipyridine)M═O + H2O]+ complexes eliminated OH upon further near-UV photodissociation. This reaction sequence can be accomplished at a single laser wavelength in the range of 260–340 nm to achieve stoichiometric homolytic cleavage of gaseous water. Structures, spin states, and electronic excitations of the metal complexes were characterized by ion–molecule reactions using 2H and 18O labeling, photodissociation action spectroscopy, and density functional theory calculations.