Ta(V) complexes of a bulky amine tris(phenolate) ligand: steric inhibition vs. chelate effect

The reactivity of a bulky amine tris(phenolate) ligand toward Ta(NMe2)5 was investigated. The reaction leading to the final product LigTa(NMe2)2 was slow and proceeded via an unusual dinuclear complex. The X-ray structures of both complexes were solved. Significantly, although the reaction of Ta(OEt)5 with that ligand precursor is slow as well, no dinuclear intermediate is observed during the reaction course.