Molecular and crystal structure of N,N'-dimethyl-5,6-diaminouracil

The x-ray study of the crystal structure of N,N-dimethyl-5,6-diaminouracil was performed. At 20 deg. C, a=7.449(3), b=11.459(4), and c=10.048(4) A; β=102.52(2) deg.; V=837(1) A3, sp. gr. P21/n; Z=4; and R=0.051 for 1044 reflections. In the crystal, the compound exists as a monohydrate. The amino groups at the C=C double bond are nonequivalent. Specific changes in the bond lengths in the NH2-C=C-C=O moiety indicate strong conjugation between one of the amino groups and the adjacent carbonyl group. The other amino group is actually expelled from conjugation and has a trigonal-pyramidal configuration. The data obtained are correlated with the compound reactivity