Structure of suriclone, a benzodiazepine receptor agonist

6-(7-Chloro-1,8-naphthyridin-2-yl)-2,3,6,7-tetrahydro-4-methyl-7- oxo-5H-1,4-dithiino[2,3-c]-pyrrol-5-yl-1-piperazinecarboxylic++ + acid, C20H20C1N5-O3S2, Mr = 477.9, triclinic, P1, a = 8.7066 (3), b = 9.7665 (8), c = 14.2515 (16) A, alpha = 80.986 (9), beta = 75.168 (6), gamma = 65.884 (5) degrees, V = 1067.4 (2) A3, Z = 2, F(000) = 496, room temperature, Dm = 1.482, D chi = 1.487 g cm-3, lambda(Cu K alpha) = 1.54178 A, Ni filter, mu = 36.3 cm-1, R = 0.053, omega R = 0.070 for the 3538 reflections included in the refinement. Comparisons of the structures of the two enantiomers of suriclone and the active conformer of the 1,4-benzodiazepine anxiolytics allow the identification of the active form of suriclone as the R isomer.