93Nb, NMR

Nb(PF3)6] has been prepared by photolysis of [Nb(CO)6]- under PF3 and studied by multinuclear NMR. The 93Nb chemical shifts suggest weaker Nb-PF3 than Nb-CO interactions.722 

In the absence of water molecules in the system, similar compositions of fluoride complexes of tantalum and niobium are expected. An analysis of the 19F and 93Nb NMR spectra of solutions based on anhydrous hydrogen fluoride, performed by Buslaev et al., revealed the presence of NbF6 and NbF72 complexes [57]. 

The almost certainly regular octahedron proposed for [M(PF3)6], (M = Cr, Mo, and W) and [VH(PF3)6], based on spectroscopic data, has not yet been substantiated by X-ray or electron diffraction methods however, the well-resolved 51V and 93Nb NMR spectra of the anions [M (PF3)6] (M = V, Nb), and the 95Mo NMR spectrum of [Mo(PF3)6] indicate that the metal atoms are certainly in a high symmetrical environment. 

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