Crystal structure of barbituric acid (1,4)-dioxane solvate at-173°C

The structure of barbituric acid (1,4)-dioxane solvate has been determined by X-ray diffraction at 100 K. The compound crystallizes in the triclinic space group P(1) over bar with cell dimensions of a = 6.7770(16) Angstrom, b = 9.583(2) Angstrom, c = 9.697(2) Angstrom, alpha = 85.868(5)degrees, beta = 82.566(5)degrees, gamma = 70.675(5)degrees, V = 589.0(2) Angstrom(3), and Z = 1. In the solid state, one asymmetric unit consists of C4H4N2O3 . 3/2(C4H8O2), each barbituric acid molecule being involved in two hydrogen bonds. The two nitrogen atoms of the acid act as hydrogen donors to two oxygen atoms, each from a different molecule of (1,4)-dioxane, which serve as the acceptors. Not all of the hydrogen-bonding capacity of the chemical moieties is used, and the principal feature of the supramolecular structure is a sawtooth ribbon composed of alternating barbituric acid and (1,4)-dioxane molecules, connected through hydrogen bonds and C-H...O interactions.