Tellurolate: an effective Te-atom transfer reagent to prepare the triad of group 5 metal bis(tellurides)

Abstract

We show in this work how lithium tellurolate Li(X)_nTeCH₂SiMe₃ (X = THF, n = 1, 1; X = 12-crown-4, n = 2, 2), can serve as an effective Te-atom transfer reagent to all group 5 transition metal halide precursors irrespective of the oxidation state. Mononuclear and bis(telluride) complexes, namely (PNP)M(Te)₂ (M = V; Nb, 3; Ta, 4; PNP^- = N[2-PⁱPr₂-4-methylphenyl]₂), are reported herein including structural and spectroscopic data. Whereas the known complex (PNP)V(Te)₂ can be readily prepared from the trivalent precursor (PNP)VCl₂, two equiv. of tellurolate, and elemental Te partially solubilized with PMe₃, complex 3 can also be similarly obtained following the same procedure but with or without a reductant, Na/NaCl. Complex 4 on the other hand is formed from the addition of four equiv. of tellurolate to (PNP)TaF₄. Having access to a triad of (PNP)M(Te)₂ systems for group 5 metals has allowed us to compare them using a combination of theory and spectroscopy including Te-L₁ edge XANES data.