ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Copper/Zinc Oxide Catalysts. VIII. Crystal Structure of Zinc Maleate Dihydrate, Zn(C₄0₄H₂)(H₂0)₂ and its Comparison with the Structure of the Cu-Zn Analogue Zn_o,94Cu_o.o6(C₄0₄H₂)(H₂0)₂

J. Černák, D. Mikloš, C. Kappenstein, I. Potočňák, J. Chomič, and F. Gérard

Department of Inorganic Chemistry, Faculty of Science, P. J. Šafárik University, SK-041 54 Košice

Abstract: Single crystals of Zn(C₄0₄H₂)(H₂0)₂ (ZMH) were prepared and the crystal and molecular structure was determined. ZMH exhibits a 2-dimensional structure formed of extended layers stacked perpendicularly to the [010] direction like the structure of the copper-zinc analogue Zn_0.94Cu_0.06(C₄0₄H₂)(H₂0)₂ (ZCMH). The layers are built up of zinc atoms, maleate anions, and the two water molecules; each bridging maleate ligand is coordinated to three different zinc atoms through three carboxylate oxygen atoms. The close coordination sphere of the zinc atom contains the water molecules as well as three carboxylate oxygen atoms with all Zn-O distances shorter than 2.137(2) Å. The fourth oxygen atom of the maleate anion is at a longer distance from zinc (2.658(2) Å) and this atom is involved in an interlayer hydrogen bond. The unit cell parameters and volume of ZMH are smaller than for ZCMH despite the higher ionic radii of Zn²⁺ in comparison with Cu²⁺. This observation can be explained by the more deformed coordination polyhedron around the copper atom, which causes less efficient packing of the layers in the structure of ZCMH.

Full paper in Portable Document Format: 545a282.pdf

Chemical Papers 54 (5) 282–288 (2000)