Heterocyclopentadienyl Complexes of Group-3 Metals

Heterocyclopentadienyl complexes of group-3 metals (scandium, yttrium, lanthanum and the lanthanides, and uranium) are compounds in which one or more −CH units of a cyclopentadienyl-like ligand have been replaced by a heteroelement (nitrogen, phosphorus, arsenic, or antimony). These ligands can have very diverse substitution patterns, notably with bridged and cavitand-like structures. In addition to the classical η5-coordination behaviour, the heterocyclopentadienyl ligand can adopt a very large array of coordination patterns. Some complexes have a very promising chemistry since they have been found to activate small molecules such as nitrogen and ethylene.