Synthesis and crystal structure of MCu(edta){center_dot}4H{sub 2}O: Molecular precursors for MCuO{sub 2} (M = Ca, Sr, Ba)

Journal Article · Sun May 01 04:00:00 EDT 1994 · Chemistry of Materials

DOI:https://doi.org/10.1021/cm00041a023· OSTI ID:83286

Insausti, M; Lezama, L; Cortes, R; Rojo, T; Pizarro, J L; Bocanegra, E H; Arriortua, M I ^[1]

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1. Universidad del Pais Vasco, Bilbao (Spain)

The compounds MCu(edta){center_dot}4H{sub 2}O (edta = ethylenediaminetetraacetic acid; M = Ca, Sr, Ba) have been synthesized and characterized by analytical and spectroscopic techniques. The structures of the strontium and barium complexes have been determined by X-ray diffraction methods. Both compounds are isostructural and crystallize in the monoclinic system, space group P2{sub 1}/c, with four formula weights in a cell measuring a = 8.717(1), b = 10.568(3), c = 19.374(3) {angstrom}, {beta} = 100.39(1){degrees} for [SrCu(edta)(H{sub 2}O){sub 3}]{center_dot}H{sub 2}O and a = 8.818(1), b = 10.200(2), c = 19.737(2) {angstrom}, {beta} = 102.40(1){degrees} for [BaCu(edta)(H{sub 2}O){sub 3}]{center_dot}H{sub 2}O. The structures were refined to R = 0.046 (R{sub w}=0.051) and R = 0.034 (R{sub w}=0.037) for strontium and barium compounds, respectively. The geometry of the complexes consists of an intricate network of ligand-bridged coordination polyhedra, where the arrangement of the copper(II) ion exhibits a distorted octahedral topology. The geometry of the alkaline-earth metal cations is near to the bicapped trigonal prism, being bound to three water molecules and five oxygen atoms from different edta molecules. In comparison with the structural results of the [CaCu(edta)(H{sub 2}O){sub 2}]{center_dot}2H{sub 2}O, a change in the coordination polyhedron of calcium ion has been established. Thermal treatment of the complexes using TGA involves three consecutive steps: dehydration, ligand pyrolysis and the formation of inorganic residue. Taking these results into account, further thermal treatments have been performed in order to obtain MCuO{sub 2} phases (M = Ba, Sr, Ca). 33 refs., 6 figs., 4 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 83286
• Journal Information: Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 5 Vol. 6; ISSN 0897-4756; ISSN CMATEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM COMPLEXES
CALCIUM COMPLEXES
CHEMICAL PREPARATION
COPPER COMPLEXES
CRYSTAL STRUCTURE
HYDRATES
MONOCLINIC LATTICES
STRONTIUM COMPLEXES
THERMAL GRAVIMETRIC ANALYSIS
X-RAY DIFFRACTION