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 n MCSe and monotelluride L n 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 n 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.