Crystal and molecular structure of 2,2,6,6-tetrafluoro-4,4,8,8-tetramethylcyclotetraphosphazene

Abstract

Crystals of 2,2,6,6-tetrafluoro-4,4,8,8-tetramethylcyclotetraphosphazene, N₄P₄F₄Me₄, are monoclinic, a= 12·910(5), b= 9·236(4), c= 12·329(5)Å, β= 117·13(3)°, Z= 4, space group C2/c. The structure was determined with diffractometer data by Patterson and Fourier syntheses and refined by full-matrix least-squares methods to R 0·081 for 444 observed reflexions. The phosphazene ring is situated on a C₂ axis and has the ‘saddle’ conformation. There are two distinct P–N bond lengths, 1·53 and 1·59 Å, which are explicable in terms of π-bonding theories.