Inverse coordination - An emerging new chemical concept. Oxygen and other chalcogens as coordination centers

Inverse coordination is the formation of metal complexes in which the arrangement of acceptor and donor sites is opposite to that occurring in conventional coordination complexes. Inverse coordination complexes are formed around a non-metal species as central atom (ion) surrounded by a number of metal atoms (ions) connected or not by internal bridging (intramolecular) linkers. This review presents a panorama of inverse coordination structures and illustrates the diversity of species which can be described under this concept. Structures are presented in which coordination centers are oxygen and the other chalcogens (sulfur, selenium, tellurium).