Advances in Transition Metal Seleno- and Tellurocarbonyl Chemistry.

In contrast to the ubiquity of transition-metal carbonyl, and (to a lesser extent) thiocarbonyl complexes, transition-metal complexes of carbon monoselenide L MCSe and monotelluride L MCTe remain scarce. The last few years, however, have seen notable steps towards expanding this chemistry, specifically with regards to new systematic studies on homologous sets of chalcocarbonyl complexes L MCE (E=O, S, Se, Te), the first reports of new bi- and polynuclear CSe and CTe bridging complexes and a confluence with metal carbido chemistry. Herein the properties, syntheses and reactions of these rare but fundamentally intriguing compounds are discussed.