Synthesis and crystal structure of new lanthanide coordination polymers with Pyridine-2, 6-dicarboxylic acid

Reactions between Ln(NO3)(3) aq (Ln = La (1), Ce (2), Pr (3) and Nd(4)), pyridine-2, 6-dicarboxylic acid (2, 6-pdc), and sodium nitroprusside Na-2[Fe(CN)(3)NO] lead to three-dimensional network structures: {[Ln(2)(2, 6-pdc)(2)(H2O)(3)][Fe(CN)(5)NO]center dot 4H(2)O}(n) (Ln = La (1), Ce (2), Pr (3) and Nd(4)). The complexes 1 and 2 crystallize in the monoclinic space group Cc while complexes 3 and 4 crystallize in the monoclinic space group I2. The Ln(III) ion is nine-coordinate by four oxygen atoms of three 2, 6-pdc ligands, four oxygen of water and one nitrogen atom of 2, 6-pdc. Ln(III) ions are bridged by 2, 6-pdc ligands via bridging/chelating-bridging pentadentate coordination to form 3-D framework structures. Hydrogen bonds provide additional stabilization of the crystal structures. The magnetic properties of 2-4 have been investigated. (C) 2015 Elsevier B.V. All rights reserved.