Adducts of chlorine oxide trifluoride with group V element pentafluorides. Structural study of the hexafluoro anions

Abstract

was studied. With each of these pentafluorides a one-to-one complex is formed and characterized by X-ray powder diffraction patterns and vibrational spectra. The latter strongly support ionic structures. Both orbital valence and Urey-Bradley force fields were computed and evaluated for

Mean Amplitudes of Vibration of Some Octahedral MF6 – Anions

“…As can be seen, the mean amplitudes for the X-F bonds diminish from PF 6 − to AsF trend agrees with the corresponding force constants, which show the inverse trend (i.e., they increase from PF 6 − to SbF 6 − and diminish again for BiF 6 − ) [5]. Interestingly, above 700 K the amplitudes for BiF 6 − are even higher than those of PF 6 − .…”

“…The values of these short F ··· F distances become continuously higher in the direction from PF 6 − to BiF 6 − , also in agreement with the decrease of the respective bending force constants in the same direction [5]. The amplitudes for the longer F ··· F distances are fairly similar in all cases but also show a slight increase in the direction from PF 6 − to BiF 6 − .…”

“…also [7,8]) which, as we have demonstrated earlier, leads to excellent results in the case of octahedral molecules and ions [9]. The necessary vibrational data were taken from the paper of Bougon et al [5], and a perfect octahedral geometry was assumed for all the calculated species.…”

“…Using the pentafluorides of the elements of groups 5 (V,Nb,Ta) and 15 (P,As,Sb,Bi) of the Periodic System as Lewis acids, it was possible to generate a number of adducts of ClOF 3 and investigate their vibrational spectra [5].…”

“…Interestingly, above 700 K the amplitudes for BiF 6 − are even higher than those of PF 6 − . Although the fact that the bonding force constants do not follow a linear trend in the full series has been interpreted as a consequence of a higher ionic contribution to the X-F bonds in the case of BiF 6 − [5], it probably arises from relativistic effects. As has been demonstrated for the hydrogen halides, a relativistic bond contraction takes place from HF to HI, but an expansion is observed for HAt.…”