Half-sandwich Imido Compounds of Niobium and Tantalum

3 Half-sandwich Imido Compounds of Niobium and Tantalum 

The lack of stability of terminal oxo compounds of the heavier Group 5 metals led us naturally to the door of the isoelectronic imido (NR) ligand, where the availability of a substituent attached to the multiply-bonded group would allow both steric and electronic modulation of the products stability and reactivity. There had been a handful of half-sandwich imido complexes of the Group 5 metals synthesised by other workers, especially for vanadium and tantalum, but at that time none were known for niobium. A half-sandwich imido compound of niobium we considered, therefore, a prime target. 

A Journey in Metal-Ligand Multiple Bond Chemistry 

4 Exploiting the Isolobal Relationship Between Cyclopentadienyl and Imido Ligands 

Having synthesised a family of metallocene look-alikes , we were interested to 

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