Vibrational spectra of eight-coordinate niobium and tantalum complexes with peroxo ligands: A theoretical simulation

A theoretical interpretation of the experimental observations made by vibrational IR and Raman spectroscopy on eight-coordinate peroxo complexes of niobium(v) and tantalum(v) is carried out. The theoretical study, realised on stoichiometric models of general formula [M(O-2)(4)](3-), [M(O-2)(3)L-2](x-), cis-and trans-[M (O-2)(2)L-4](y-) and [M(O-2)L-6](z-) (M = Nb-v or Ta-v), provides the normal modes of vibrations involving peroxo ligands, their corresponding calculated frequency and their activity in IR and/or Raman spectroscopy. The theoretical results from the model complexes are compared with experimental IR and Raman spectroscopic data. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).