Abstract
The reaction kinetics and mechanisms of catalytic oxygen atom transfer (OAT) with rhenium oxazoline and thiazoline complexes are described in this feature article. The striking features of this new family of molecular oxotransferases are their rapid kinetics and their surpassed ability in catalyzing the very difficult reduction of perchlorate by atom transfer. The diverse and competing pathways that make these catalysts efficient and practical have been delineated. Factors that govern the rates of OAT reactions have been elucidated on the basis of substrate variation, substituent and steric effects, subtle changes in the coordination environment, and geometrical transformations. This account also presents comparisons of our abiological OAT catalysis to mechanistically related enzymes and model complexes of molybdenum and tungsten.