Crystal and molecular structure of 2,cis-4,trans-6-triphenyl-2,4,6-trithioxo-1,3,5,2,4,6-trioxatriphosphorinan

Abstract

Crystals of the title compound (Ia) are monoclinic, space group P2₁/c with a= 12·257(10), b= 9·299(7), c= 21·027(17)Å, β= 119·77(17)°. The structure was solved by direct methods. Diffractometer data for 3148 planes were refined by block-diagonal least-squares to R 0·043. The boat-like six-membered ring approximates closely to the symmetry m(C₈): five of the constituent atoms are coplanar to within 0·04 Å while the sixth, an oxygen atom, is displaced 0·32 Å from this plane. Two phenyl groups and one sulphur atom lie on one side of the heterocyclic ring and the other phenyl group and two sulphur atoms on the other side. The mean lengths of the chemically equivalent bonds are: P–C 1·779(4), PS 1·896(2), P–O 1·613(3), and CC 1·383(7)Å.