Structural characterization of two lanthanide compounds based on polyoxometalate building units

Abstract

Two new compounds [Hbpy]₂[Ce(Hbpy)(DMF)₅(H₂O)₂][H₂W₁₂O₄₀] · 0.5H₂O (1) and [La(DMF)₇(H₂O)][PMo₁₂O₄₀] · DMF · (CH₃)₂NH (2) (DMF = N,N-dimethylformamide, bpy=4,4′-bipyridine) have been synthesized and characterized by single-crystal X-ray diffraction, IR spectra, TG analysis and electrochemical analysis. In 1, the [Ce(Hbpy)(DMF)₅(H₂O)₂]⁴⁺ unit is supported on the α-Keggin polyoxoanion [H₂W₁₂O₄₀]⁶⁻ via bridging oxygen atoms, and further extended into 2-D supramolecular networks by hydrogen-bonding and π–π interactions. There exist one-dimensional channels surrounded by supramolecular interactions, in which 4,4′-bipy ligands reside. Compounds constructed from Ln(III) and [H₂W₁₂O₄₀]⁶⁻ polyoxoanions are rare. For 2, the [La(DMF)₇(H₂O)]³⁺ is supported by [PMo₁₂O₄₀]³⁻ units via the surface bridging oxygens, and further extended into 2-D supramolecular networks through hydrogen bonds. As for 1, a one-dimensional channel exists in 2, in which DMF resides. To our surprise, (CH₃)₂NH molecules exist in the structure of 2, from hydrolysis of DMF under catalysis of 12-molybophosphate. The electrochemistry of 1 is investigated.

Keywords:

• Polyoxometalate
• Lanthanide cations
• Supramolecular networks
• Hydrogen bond
• Electrochemical property

Acknowledgements

Supported by National Science Foundation of China (No. 20371011); Science and Technology Development Project Foundation of Jilin Province (No. 20060420); Analysis and testing foundation of Northeast Normal University (No. 201586000/201372000); Ph.D station Foundation of Ministry of Education (No. 20060200002); Science Foundation for Young Teachers of Northeast Normal University (No. 20070303).