Abstract
The structure of the title compound, C10H6N4O2, reported by Smalley et al. [(2021). Cryst. Growth Des.
22, 524–534] from powder diffraction data and 15N NMR spectroscopy, is confirmed using low-temperature data from a twinned crystal. The tautomer in the solid state is alloxazine (1H-benzo[g]pteridine-2,4-dione) rather than isoalloxazine (10H-benzo[g]pteridine-2,4-dione). In the extended structure, the molecules form hydrogen-bonded chains propagating in the [0\overline{1}1] direction through alternating centrosymmetric R
2
2(8) rings with pairwise N—H...O interactions and centrosymmetric R
2
2(8) rings with pairwise N—H...N interactions. The crystal chosen for data collection was found to be a non-merohedral twin (180° rotation about [001]) in a 0.446 (4):0.554 (6) domain ratio.
Funder
National Institute of General Medical Sciences
US Department of Education
Louisiana Board of Regents
Publisher
International Union of Crystallography (IUCr)
Subject
Organic Chemistry,Inorganic Chemistry,Analytical Chemistry