The Raman and infrared spectra of the fluorosulfites of
K+, Rb+, Cs+,
NH4
+, and Me4N+
have been examined.
Previous assignment of the fundamental vibrations is revised, and
an ab initio study of the SO2F- anion is
presented.
For the pyramidal anion of symmetry
C
s
, distances of r(S−O)
= 1.458 Å and r(S−F) = 1.698 Å have
been
calculated. The heat of formation of
Me4NSO2F (−14.0 kcal/mol) was derived
from the dissociation pressure of
the salt. In addition, the lattice energy of
Me4NF (159.2 kcal/mol) was calculated from a
thermochemical cycle.
The thermochemical data are discussed in terms of reactivity of
the fluorides and stability of the fluorosulfites.