8-Acid derivative of the antitumour agent mitozolomide

The crystal structure of 3-(2-chloroethyl)-3,4-dihydro-4-oxoimidazo[5,1-d][1,2,3,5]tetra zine-8- carboxylic acid, C7H6CIN5O3, a derivative of the novel bicyclic antitumour agent mitozolomide, 3-(2-chloroethyl)-3,4-dihydro-4-oxoimidazo[5,1-d][1,2,3,5]tetra zine-8- carboxamide, has been determined at 293 K. The expected dimer, hydrogen bonded via the two carboxyl groups, does not occur. In preference, the two molecules in the asymmetric unit utilize hydrogen bonding between the carboxyl group of one and the N atom and CH in the imidazo ring of the other. These two then further interact via the same scheme with their centrosymmetrically related pair to produce a fully hydrogen-bonded planar tetramer.