The crystal structure of zinc(II) fumarate tetrahydrate

The crystal structure of zinc fumarate tetrahydrate, ZnC 4 H 2 0 4 • 4 H 2 0 , has been determined using three-dimensional single crystal X-ray data. The crystals are monoclinic, space group /21/c, Ζ = 4, with a = 7.58(2), b = 14.46(3), c = 7.66(2) Â, β = 101.2(1)°. The structure was solved by the heavy-atom method and refined by least-squares using 692 independent observed reflexions to a final R-value of 0.12. The zinc atom is surrounded by six oxygen atoms, at the corners of a distorted octahedron. Both the carboxyl groups in the molecule are twisted out of the plane containing the carbon atoms by angles of 49.4° and 15.8°. Crystal data The unit cell was determined from rotation and Weissenberg photographs and gave: monoclinic with a = 7.58(2), 6=14.46(3), c = 7.66(2)Â, β= 101.2(1)°, Dobs = 2.03 M g m 3 , Dcil = 2.03 Mg m" 3 , Ζ = 4, space group P2i/c. X-ray data were recorded by Weissenberg photography with CuKa radiation. A total of 692 reflexions were observed and their intensities estimated visually. Usual corrections were applied and the data brought to absolute scale by statistical methods. The structure determination and refinement The structure was solved by the heavy-atom method; heavy atoms with six oxygen atoms forming part of the metal-oxygen polyhedron were located from a three-dimensional Patterson map. Iterative Fourier syntheses 152 Short Communicat ion ^ ΰ ^ o I Ο «Λ c· O — f"ì —