Peroxides in metal complex catalysis

• Peroxides as versatile ligands in coordination chemistry. • Peroxides as valuable oxidants, initiators or substrates in metal complex catalysis. • Mechanisms of metal complex catalyzed peroxidative oxidation reactions. Peroxides form an important class of chemicals in which two oxygen atoms are linked together by a single covalent bond (R−O−O−R, R=H, SO 3 K, alkyl, etc.), with a wide range of applications in medicine, industry, environmental protection, etc. The current version of the Cambridge Structural Database reveals more than 1400 structurally characterized metal-peroxy/peroxo complexes with diverse coordination modes having specific biological, catalytical and other functional properties. Both inorganic and organic peroxides are versatile oxidants and extensively used reagents for metal complex catalyzed functionalization of organic compounds. The utilization of peroxides in metal complex catalysis typically requires prior activation of O−O or O−R bonds at a metal centre leading to radical species with a reactivity and lifetime that are dependent on the substituents R and reaction medium (pH, solvent, etc.). In fact, the cooperation of a metal centre (coordination) with a peroxide can lead to a multifunctional catalytic system having a high performance towards selective functionalization of organic substrates. This review is intended to focus on the auxiliary/crucial role of peroxides in the transformations of various classes of organic compounds such as alkanes, alkenes, alkynes, aromatics, heterocycles, aldehydes, ketones and alcohols, catalyzed by metal complexes.