STRUCTURE AND CONFORMATION OF THE 1-1 MOLECULAR-COMPLEX SULFAPROXYLINE-CAFFEINE

rho-Isopropoxy-N-sulfanilylbenzamide-3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione (1/1), C16H18N2O4S.C8H10N4O2, M(r) = 528.58, monoclinic, P21/c, Z = 8, a = 12.197 (1), b = 34.109 (5), c = 12.878 (1) angstrom, beta = 108.68 (1)degrees, V = 5075.4(1.0) angstrom-3, D-chi = 1.38 g cm-3, Cu K-alpha, lambda = 1.5418 angstrom, mu = 15.32 cm-1, F(000) = 2224, T = 293 K, final R = 0.046 for 5997 observed reflections with F greater-than-or-equal-to 3 sigma (F). The asymmetric unit contains two sulfaproxyline and two caffeine molecules. In the crystal the flat caffeine molecule is packed parallel to another caffeine molecule. Hydrogen bonds, where present, are weak (D...A lengths > 3.0 angstrom), showing that the packing is dominated by the non-bonded interactions.