Syntheses, structures, and properties of multidimensional lithium coordination polymers based on aliphatic carboxylic acids

Abstract

Three lithium coordination polymers, [Li₄(H₂O)₂(EDTA)] (1), [Li₄(H₂O)₄(BTCA)] (2), and (H₂NMe₂)₂[Li₂(H₂O)₂(BTCA)] (3) (H₄EDTA = ethylenediaminetetraacetic acid, H₄BTCA = 1,2,3,4-butane tetracarboxylic acid, H₂NMe₂ = dimethyl amine), have been synthesized by reacting lithium salts with aliphatic carboxylic acids using a solvothermal method. The structures of all the three complexes have been determined by single crystal X-ray diffraction studies. The single crystal structure analysis revealed that complex 1 has a three-dimensional framework, whereas complex 2 has 2D sheets and complex 3 has 1D chains. In addition, these lithium complexes contain various inorganic motifs with a tetramer in 1 and 2, and discrete tetrahedra in 3 and have further been connected through organic ligands to construct multidimensional structures. Further, the electrochemical properties of complexes 1–3 have been studied to evaluate these compounds as electrode materials for lithium ion batteries with discharge capacities of around 100 mA h g⁻¹ in the first thirty cycles.