Structure of 2-[7-chloro-2(3H)-oxo-5-phenyl-1H-1,4-benzodiazepin-1-yl]ethyl hydrogen succinate N4-oxide, C21H19ClN2O6

M r = 430.84, monoclinic, P2Jn, a = 17.269(3), b=9.823(3), c=11.477(3)/k, fl= 98.48 (3) °, U= 1925.6 (9)/k 3, Z = 4, D x = 1.49Mgm -3, T=298K, 2=1.54178/k, F(000)= 896, p(Cu Kct) = 2.019 mm -1, R = 0.039 for 2474 reflections with I o >_ 3O(lo). The compound displays very low binding affinity for the benzodiazepine receptor. Its structure is compared with those of other benzodiazepines having high affinity and it is found that small geometrical differences are unimportant in determining the biological activity of benzodiazepines when compared with the role played by the ring substituents.