Acta Crystallographica Section C

Crystal Structure Communications

Volume 64, Part 8 (August 2008)

metal-organic compounds

 

A novel three-dimensional heterometallic coordination polymer: poly[[hexaaquabis[₃-3,5-dicarboxylatopyrazolato-⁵O³,N²:N¹,O⁵:O^5'](₂-oxalato-⁴O¹,O²:O^1',O^2')copper(II)dierbium(III)] trihydrate\]

Y. Wang and Y.-Z. Shen

Abstract: The title novel heterometallic 3d-4f coordination polymer, {[CuEr₂(C₅HN₂O₄)₂(C₂O₄)(H₂O)₆]·3H₂O}_n, has a three-dimensional metal-organic framework composed of two types of metal atoms (one Cu^II and two Er^III) and two types of bridging anionic ligands [3,5-dicarboxylatopyrazolate(3-) (ptc^3-) and oxalate]. The Cu^II atom is four-coordinated in a square geometry. The Er^III atoms are both eight-coordinated, but the geometries at the two atoms appear different, viz. triangular dodecahedral and bicapped trigonal prismatic. One of the oxalate anions is located on a twofold axis and the other lies about an inversion centre. Both oxalate anions act as bis-bidentate ligands bridging the latter type of Er atoms in parallel zigzag chains. The pdc^3- anions act as quinquedentate ligands not only chelating the Cu^II and the triangular dodecahedral Er^III centres in a bis-bidentate bridging mode, but also connecting to Er^III centres of both types in a monodentate bridging mode. Thus, a three-dimensional metal-organic framework is generated, and hydrogen bonds link the metal-organic framework with the uncoordinated water molecules. This study describes the first example of a three-dimensional 3d-4f coordination polymer based on pyrazole-3,5-dicarboxylate and oxalate, and therefore demonstrates further the usefulness of pyrazoledicarboxylate as a versatile multidentate ligand for constructing heterometallic 3d-4f coordination polymers with interesting architectures.

Formula: [CuEr₂(C₅HN₂O₄)₂(C₂O₄)(H₂O)₆]·3H₂O

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