Bis[7-(1,3-dioxolan-2-yl-methyl)-3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione] dichlorozinc(II) 0.47-hydrate: the role of secondary bond in forming the four-fold helix Chain

Single crystals of ZnIICl2(C11H14N4O4)2 · 0.47H2O (I) were obtained from an aqueous solution of ZnCl2 and doxofylline in a 1: 2 molar ratio, and the crystal structure was determined by single-crystal X-ray diffraction (tetragonal, space group P41, Z = 8, a = b = 14.9481(5), c = 25.4778(11) Å). In the compound I, Zn2+ cation is located at the center of a distorted tetragonal coordination polyhedron, formed by the two Cl atoms and two N atoms of doxofylline ligands. In the crystal, crystallographically independent molecules of the compound I are bonded alternatively together by Cl···N secondary bonds to form four-fold helix chain along the z axis.