1-Methyl-5,6,7,8-tetrahydroquinoxalin-2(1H)-one

The title compound, C(9)H(12)N(2)O, crystallizes in a triclinic unit cell, with two crystallographically independent molecules in the asymmetric unit. The two independent molecules adopt different modes of packing. One type of molecule is arranged in infinite columns, while the other type packs as dimers, forming spacers between the parallel columns. Each type of molecule is arranged in pairs related by inversion centers. The distances between potential reaction centers are 3.395 (2), 3.457 (2) and 3.522 (2) A. As a result of the symmetry of the pairs and the close distances between the potential photoreactive centers, it is expected that the dimer will be the anti-trans isomer.