Stable structures, radial electron densities and chain flexibilities of fou
r poly(thionylphosphazenes) model compounds with basis chemical composition
S(OX)(R2PN)(2) (X: F or CI and R: Cl or CH3) were studied at the level of
density functional theory with the polarized double zeta valence basis set.
All possible conformations and energies associated with rotation about N-P
and N-S were obtained. All mimics adopt a non-planar trans-cis conformatio
n in the lowest energy state. The conformational energy differences for rot
ations around bonds of the PTP backbone range from 0.5 to 5 kcal mol(-1). T
hese results were found to be consistent with the other ab initio studies p
erformed on similar model compounds. Structural and conformation difference
s between mimics are discussed. Particular attention is paid to the effects
of the end groups on the structure of mimics. (C) 1999 Elsevier Science B.
V. All rights reserved.