Four new coordination polymers constructed from benzene tricarboxylic acid: synthesis, crystal structure, thermal and magnetic properties

Abstract

The use of 1,3,5-benzene tricarboxylic acid (H3btc) as an organic linker has allowed us to achieve the rational design of two pairs of isostructural coordination polymers having molecular formulae [M2(btc)(F)]n (M(II) = Mn (1), Co (2)) and [M3(btc)(Hbtc)(OH)(H2O)11]n (M(II) = Fe (3), Co (4)) where btc and Hbtc represent the fully and doubly de-protonated tricarboxylates respectively. These compounds were synthesized using hydrothermal methods and characterized by thermal analysis and variable temperature magnetic measurements. The X-ray analysis reveals that compounds 1 and 2 crystallize in the monoclinic space group C2/c while compounds 3 and 4 crystallize in the monoclinic space group C2. Compounds 1 and 2 feature fluoride bridged 1D metal chains linked together via carboxylate groups of btc, whilst compounds 3 and 4 consist of 1D zigzag chains having strong hydrogen bonds with neighbouring chains. Variable temperature magnetic measurements show an overall antiferromagnetic behaviour for compounds 1, 2 and 4, with no indication of magnetic ordering phenomena in the temperature range from 300–2 K. As 3 and 4 are isostructural, we assume that the magnetic properties are similar. © 2010, Royal Society of Chemistry