STRUCTURE OF A CHIRAL TRICYCLIC PHOSPHONAMIDE

2-[1-(1,3-Dithiolan-2-ylideneamino)-3-butenyl]-2,3,3a,4,5,6,7,7a-octahydro-1,3-dimethyl-1H-1,3,2-benzodiazaphosphole 2-oxide, C15H26N3OPS2, M(r) = 359.48, trigonal, P3(1)21, a = b = 9.778 (7), c = 34.214 (1) angstrom, V = 2832.9 angstrom 3, Z = 6, D(x) = 1.264 Mg m-3, lambda-(Cu K-alpha) = 1.54178 angstrom, mu-(Cu K-alpha) = 3.37 mm-1, F(000) = 3552, T = 190 K, R = 0.046 for 1991 observed reflections. The title compound contains two heterocyclic rings, a 1,3-diazaphosphole 2-oxide and a 1,3-dithiolanylideneaminobutene bonded to the P atom which is tetrahedrally coordinated. Both five-membered rings are in the half-chair conformation. The diaza ring is trans-fused to a cyclohexane which is in the chair conformation. The absolute configuration at the carbon center alpha-to phosphorus is R.