Crystal structure of compounds with (N–P)n rings. Part X. Decarbomocyclopentaphosphazene, N5P5Br10

Abstract

The title compound, crystallizes in space-group P with unit-cell dimensions a= 13·760(2), b= 9·352(1), c= 10·329(1)Å, α= 93·78(1), β= 122·57(1), γ= 107·27(1)°, Z= 2. The structure was solved from diffractometer data (110 K) by the symbolic addition method and refined by block-diagonal least-squares analysis to R 0·12 for 3260 observed reflexions. The molecule has a pseudo-mirror plane passing through a PBr₂ group and the opposite nitrogen atom. The ten-membered ring is puckered with a phosphours atom deviating 0·54 Å from the average ring plane and with one re-entrant angle at a nitrogen atom. The mean P–N and P–Br bond lengths are 1·571(17) and 2·175(6)Å. The N–P–N angles fall into two different groups [mean values 120·5(9) and 114·3(9)°] and there are three kinds of P–N–P angles [mean values 143·8(10), 136·6(11), and 131·2(11)°]. There are some short intermolecular Br⋯Br distances (3·45, 3·45, and 3·48 Å).