Far-infrared spectra (20–450 cm.–1) of some halide cluster compounds of niobium and tantalum

Abstract

The far-infrared spectra of M₆X₁₄(M = Nb or Ta; X = Cl or Br) compounds have been recorded as anhydrous solids, hydrates, and pyridine adducts and in solution. The spectra all contain four strong bands and the positions and intensities of these absorptions are characteristic of M₆X₁₂²⁺ ions. The complexity of the spectra increases in the series M₆X₁₄in solution < M₆X₁₄,8H₂O < M₆X₁₄(anhydrous), and these results are interpreted in terms of deviations from the octahedral structure of an isolated M₆X₁₂²⁺ cluster unit.