Structure of 5,5-dimethyl-2-phenylimino-Δ³-1,3,4-thiadiazoline from oxidative cyclization of a thiosemicarbazone

Abstract

The X-ray crystal structure of 5,5-dimethyl-2-phenylimino-A3-1,3,4-thiadiazoline, CloHI [N3S, has been determined. The compound is monoclinic, P 2 ' / c (No. 14), with a = 13.200(5), b = 6.340(4), and c = 13.823(4) A, P = 113.50(4)", and Z = 4.The structure was determined by direct methods and refined to R = 0.061, R,, = 0.067 for 1277 unique reflections. The molecule has the Z configuration. The thiadiazoline ring is planar. C-N and N=N bond lengths are within the normal range. The C-S bond lengths are similar to those we have observed previously in thiazolidines. Angles differ markedly from an expected average 108". The small C-S-C angle (90.6(2)") is accompanied by larger C-N=N angles (1 14.9(3), 1 17.8(3)"). The phenyl ring is not coplanar with the thiadiazoline ring (dihedral angle 38.6(4)") because of repulsive interaction of the phenyl o-hydrogen atom with the sulphur atom.