ALPHA-IMINOHYDROXYLAMINE-ALPHA-AMINONITRONE TAUTOMERISM - A 1 1 MIXTURE OF 2 TAUTOMERIC FORMS IN CRYSTALS OF -DIHYDRO-1H-IMIDAZOL-2-YL)-N-PHENYL-HYDROXYLAMINE/

Crystals consisting of two distinct chemical entities, tautomers of ea ch other, in exact 1:1 ratio, have been obtained and their structure d etermined by X-ray analysis. The crystals of C9H11N3 . C9H11N3 are mon oclinic, P2(1)/c, a = 15.674(3), b = 17.085(3), c = 13.758(3)Angstrom, beta = 90.78(2)degrees, Z = 8. There are two hydroxylamine and two am inonitrone molecules in the asymmetric unit. Hydrogen bonds connect th ose molecules into chiral layers. Layers of opposite chirality alterna te and the crystal is centrosymmetric as a whole, Within those layers chains of tautomers joined by very strong O-H ... O and strong N-H ... N bonds can be recognized. Proton transfer along those chains with si multaneous rearrangement of pi-bonds within the molecules would result in interconversion of tautomers and would affect: chirality of the la yer.