Photoinduced linkage isomers of transition-metal nitrosyl compounds and related complexes

More than 20 years after the discovery of novel features introduced upon light-irradiation of nitrosyl compounds and six years since their identification as linkage isomers, it is apparent that photoinduced linkage isomerism of di- and triatomic molecules bonded to transition-metal atoms is a quite common phenomenon. Many of the new species decay close to ambient temperatures, and thus, though transient, will have relatively long lifetimes at physiological temperatures. Their role in the kinetics of biological processes remains to be elucidated. The new species may have unusual reactivity, which merits further attention.