Molecular structures of cyclic mono- and di-(phosphoranylidene)aminophosphazenes: small-molecule models for high polymers

Abstract

The molecular structures of four cyclic (phosphoranylidene)aminophosphazenes were determined. These compounds are small-molecule models for the corresponding high polymeric phosphazenes. The solid-state structures of gem-N₃P₃Cl₄[NP(OPh)₃]₂4, gem-N₃P₃(OPh)₄[NP(OPh)₃]₂5, N₃P₃(OPh)₅NP(OPh)₃6 and N₃P₃(NHPr)₅NP(NHPr)₃·HCl 7 were determined by single crystal X-ray diffraction. Structural parameters: 4, triclinic, space group P, a= 12.900(2), b= 13.035(1), c= 14.349(6)Å, α= 67.85(2), β= 80.68(3), γ= 67.73(1)°, Z= 2; 5, monoclinic, space group P2₁/n, a= 20.844(12), b= 13.679(3), c= 22.488(4)Å, β= 116.91(3)°, Z= 4; 6, triclinic, space group P, a= 18.511(11), b= 23.206(26), c= 10.701(4)Å, α= 98.67(5), β= 95.32(4), γ= 97.68(6)°, Z= 4 with two distinct molecular conformations; 7, triclinic, space group P, a= 13.187(10), b= 14.014(13), c= 14.335(4)Å, α= 96.41(4), β= 115.76(5), γ= 115.12(5)°, Z= 2. Two interesting features of compound 7 are the presence of two long P–N bonds 1.686(9) and 1.676(8)Å, and two narrowed N–P–N angles, 108.9(4) and 109.7(5)°, in the phosphazene ring.