Synthesis, structure and magnetic properties of a two-dimensional polymer based on sandwich-type tetra-cobalt(II)-substituted polyoxotungstate anions and 1-D potassium-chains

Abstract

A 2-D coordination polymer, (C₇N₄H₁₆)₂{NH(CH₃)₃}[{K(H₂O)}₄Na(H₂O)₅{Co₄(H₂O)₂(B-α-PW₉O₃₄)₂}]·2H₂O (1), was hydrothermally synthesized and structurally characterized by IR spectroscopy, elemental analysis, X-ray powder diffraction, and X-ray single-crystal crystallography. Crystal structure analysis shows a triclinic space group Pī with a = 12.4677(8) Å, b = 12.5054(8) Å, c = 18.5745(1) Å, α = 73.3220(1)°, β = 87.1890(1)°, γ = 62.2710(1)°, and V = 2443.4(3) ų. Sandwich-type tetra-cobalt(II)-substituted [Co₄(H₂O)₂(B-α-PW₉O₃₄)₂]¹⁰⁻ of 1 consists of two trivacant Keggin [B-α-PW₉O₃₄]⁹⁻ moieties and a rhomb-like Co₄O₁₆ unit. Each sandwich-type polyoxotungstate subunit connects 12 K(1) and K(2) centers from two adjacent 1-D K-chain units resulting in an interesting 2-D layer framework. Magnetic properties of 1 have been investigated.

Keywords:

• Polyoxotungstate
• Sandwich type
• Crystal structure
• Magnetic properties

Acknowledgments

This work was supported by the National Natural Science Foundation of China, the Natural Science Foundation of Henan Province, the Foundation of Henan Educational Committee of China, the Foundation for University Youth Key Teacher of Henan Province of China, and the Foundation Co-established by the Province and the Ministry of Henan University.