First amido-functionalized niobium and tantalum complexes of the ansa-structural type: Synthesis and photochemical Si-N bond cleavage

Niobium(V) and tantalum(V) amides [(eta(5)-C5H4)-Si(CH3)(2)-NR]M[N(CH3)(2)](3) (R = C6H5) containing chelate-type C, N-Ligands are available in 45% (M = Nb) and 60% (M = Ta) isolated yield, respectively, from the homoleptic amides MIN(CH,),J, and the N-functionalized cyclopentadiene C5H5-Si(CH3)(2)-NHR by double amine elimination. The niobium and tantalum derivatives undergo an unprecedented photo-induced rearrangement at room temperature, yielding the imido complexes [(eta(5)-C5H4)-Si(CH3)(2)-N(CH3)(2)]M(=NR)[N(CH3)(2)](2) as a result of S-N bond cleavage.