LASER-RAMAN SPECTROSCOPIC STUDY OF THE VAPOR-PHASE OF NBCL5 AND MIXTURES OF NBCL5 AND SNCL2

Vapour-phase Raman spectra of NbCl5 at temperatures between 418 and 58 0 K and of 1:1, 1:2 and 2:1 mixtures of NbCl5 and SnCl2 at temperature s between 359 and 676 K have been recorded. Several features have been observed in spectra from the mixtures which do not correspond to thos e known for the pure components and these vibrational bands have been assigned to the vapour-phase complex NbSnCl7. Normal coordinate analys is has been carried out for the proposed structure of the complex. Com plexation of the two components is shown to enhance the volatility of NbCl5 by a factor of 3.75 at 420 K. SnCl2 is shown to be more volatile when complexed with NbCl5 than in its pure phase. Predicted vibration al band wavenumbers from force constant calculations, combined with ob served wavenumbers have been used to calculate values for the heat cap acity, C-p(o), the enthalpy, H-T(o)-H-298(o) and the entropy, S-T(o) - S-0(o), of NbSnCl7 (g) from 0 to 6000 K.