Cyclic inorganic compounds. Part XIV. Crystal and molecular structure of 1,cis-3,trans-5,trans-7-tetrakis(dimethylamino)-1,3,5,7-tetrafluorotetraphosphonitrile

Abstract

Crystals of the title compound are monoclinic with a= 10·18 ± 0·02 b= 9·00 ± 0·02, c= 13·04 ± 0·02 Å. and β= 123·1°± 0·1°, space group P2₁/c with Z= 2. The atomic positions have been determined by Patterson and Fourier methods and refined by least-squares to R 0·073 (1281 reflexions) from X-ray diffraction data. The molecule has a centre of symmetry and the eight-membered P₄N₄ ring has a chair conformation. The mean P–N ring bonds are 1·55 Å and the mean P–N–P and N–P–N angles are 139·5 and 121·3°. The four phosphorus atoms are coplanar with two pairs of non-equivalent nitrogen atoms displaced 0·40 and 0·19 Å from the plane. The mean P–N(amine) bond is 1·61 Å implying a high π-bond order.