STRUCTURE OF 3,3-DIETHYL-1,2-DIPHENYL-1,4,2-DIAZAPHOSPHOLIDIN-5-ONE 2-OXIDE

C18H21N2O2P, M(r) = 328.35, monoclinic, P2(1)/c, a = 9.232 (3), b = 14.561 (1), c = 12.446 (3) angstrom, beta = 91.07 (1)-degrees, V = 1673 (2) angstrom3, Z = 4, D(x) = 1.304 Mg m-3, lambda(Cu K-alpha) = 1.54184 angstrom, mu = 1.54 mm-1 F(000) = 696, room temperature, R = 0.050 for 2123 reflections with I > 3-sigma(I). The five-membered ring is close to planar with deviations from the least-squares plane in the range - 0.069 (2) to 0.075 (1) angstrom. The P-N and P-C distances within the ring are 1.687 (1) and 1.862 (1) angstrom, respectively. The phenyl group attached to P(1) adopts an axial position while the O atom and phenyl group attached to C(1) and N(1), respectively, adopt equatorial positions. Two molecules (related by a centre of symmetry) are connected by two intermolecular hydrogen bonds of length 2.879 (3) angstrom between N(2) and O(2), thus forming dimers in the crystal.