The crystal structure of N,N '-bis-(1,3-dihydroxy-2-methylprop-2-yl)-pyrazine-2,3-dicarboxamide semihydrate

Crystals of the title compound were obtained by recrystallization of N,N'-b is-(1,3-dihydroxy-2-methylprop-2-yl)-pyrazine-2,3-dicarboxamide in aqueous methanol. C14H22N4O6. 1/2H(2)O crystallizes in the triclinic system, s.g. P (1) over bar (No. 2) with a = 9.339(4) Angstrom, b = 13.218(9) Angstrom, c = 14.5137(9) Angstrom, alpha = 70.95(4)degrees, beta = 87.66(4)degrees, ga mma = 87.13(4)degrees, Z = 4. Its crystal structure has been determined fro m diffractometer data and refined to a conventional R of 0.050 (4008 observ ations, 464 variable parameters). The structure contains two crystallograph ically independent molecules which are alternatingly stacked above each oth er along the [001]-direction. Extensive intermolecular hydrogen bonding bet ween these stacks leads to the formation of slabs parallel to (010). The hy drate water is only loosely attached to one of the molecules and has no app arent influence on the stacking.