文摘
Intraannular ring alternation in heterogeneously substituted cyclotriphosphazenes is investigated using both abinitio 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* basisfor use with both Hartree-Fock and the B3LYP and B3PW91 functionals. Analysis of orbitals and charges showsthat the bonding is best described using a polarized bond model rather than the previous explanation of asymmetricnitrogen-lone-pair donation into the phosphorus-nitrogen bond.