From planar to nonplanar cyclotriphosphazenes

A possible existence of planar (PNX2)3 cyclotriphosphazene, where X = H, F, Cl and Br, or nonplanar (PXNX)3 was studied at the B3LYP/6-311++G∗∗ and MP2/6-311++G∗∗ level of calculations. A linear correlation of total electronic energy difference (ΔE = Enonplanar − Eplanar) on electronegativity of the X substituent was observed. The more stable nonplanar form was predicted (ΔE = −43.49 kcal/mol) only in case of X = H. The remaining planar halogenocyclotriphosphazenes are more stable, in agreement with a few available experimental data.