Synthesis and characterization of two 3-D polymeric lanthanide complexes constructed from 1,2,4,5-benzenetetracarboxylic acid

Abstract

Two new 3-D lanthanide coordination polymers, [CeK(btec)(H₂O)₂] _n (1), [Ho(btec)_0.5(ad)_0.5(H₂O)] _n (2) (H₄btec = 1,2,4,5-benzenetetracarboxylic acid, H₂ad = adipic acid), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analyses reveal that both complexes crystallized in monoclinic space group P2₁/c and possessed 3-D net-structures. In 1, btec adopts two types of coordination modes: µ₁₂–η²:η²:η²:η¹:η²:η²:η²:η¹ bridging mode linking six Ce(III) ions and six K⁺ ions and the other µ₈–η¹:η²:η²:η¹:η¹:η²:η²:η¹ bridging mode connecting four Ce(III) ions and four K⁺ ions. In 2, btec adopts a µ₆-bridging with each carboxylate group of btec ligand in a µ₂–η¹–η² mode, the adipate is µ₄-bridging with each carboxylate µ₂–η¹–η¹-monodentate. The topological analysis shows that 1 can be simplified to a 3-nodal net with the Schläfli symbol {3²,4⁸,5³,6²}₄{3⁴,4¹²,5¹²}{4³⁸,6²⁶,8²} and 2 can be simplified to a 3-nodal network with the Schläfli symbol {4²,8⁴}{4⁶,6⁶,8³}{4⁷,6³}₂. The thermogravimetric analyses and the X-ray powder diffraction of 1 and 2 are discussed.

Keywords:

• Lanthanide coordination polymers
• 1,2,4,5-Benzenetetracarboxylic acid
• Adipic acid
• Crystal structure
• Thermogravimetric

Acknowledgments

This work was supported by the grants of the National Natural Science Foundation of China (Grant No. 21071071), the Education Foundation of Dalian city in China (Grant No. 2009J21DW004) for financial assistance, and the State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, P.R. China (Grant No. 2010–15).