The origin of endocyclic bond length variations in disubstituted cyclotriphosphazenes.
Intraannular ring alternation in heterogeneously substituted cyclotriphosphazenes is investigated using both ab initio and density functional methods. Comparisons of the calculated geometries for N3P3X6 (X = H, F, Cl, Me, Ph) and N3P3X4Y2 (X = F, Cl; Y = Me, Ph, X, Cl) with experimental X-ray data establish the utility of the 6-31G* basis for use with both Hartree-Fock and the B3LYP and B3PW91 functionals. Analysis of orbitals and charges shows that the bonding is best described using a polarized bond model rather than the previous explanation of asymmetric nitrogen-lone-pair donation into the phosphorus-nitrogen bond.
Calichman
Michael
M
Department of Chemistry, University of Vermont, Burlington, Vermont 05405-0125, USA.
Derecskei-Kovacs
Agnes
A
Allen
Christopher W
CW