Structure of trans-5-iso­propyl-1,3-di­phenyl-5-propyl-1λ6,3λ6,2,4,6,5λ5-di­thiatri­aza­phosphorine 1,3-dioxide

C18H24N302PS2, Mr=409.5 , monoclinic, P21/n, a = 13.432 (6), b = 16.727 (4), c = 9.602 (2) A, fl=110.21(3) ° , V=2025(1)A 3, Z=4, Dx= 1.343 gcm -3, 2(Mo K~) = 0.71073 A, /L = 3.5 cm -~, F(000) = 864, T- 295 K, R = 0.053 for 1628 observed reflections. The inorganic ring possesses a twistboat conformation with the phenyl substituents in trans positions. Mean bond lengths are N-P = 1.608 (3), N-S (from segment SNS)= 1.568 (4), N-S (from segment PNS)= 1.544 (3)A. The average endocyclic angles at S and N are 114.3 (2) and 124.4(5) ° respectively. The endocyclic angle at P amounts to 113.0(2) °