Synchrotron study of poly[[di-μ-aqua(μ-2,2′-bipyridyl-5,5′-dicarboxylato)dipotassium] dihydrate]

Abstract

The title compound, {[K2(C12H6N2O4)(H2O)2]·2H2O}n, forms a three-dimensional coordination polymer in the solid state. The asymmetric unit consists of one K+ ion, half of a 2,2′-bipyridyl-5,5′-dicarboxylate ligand, one coordinated water molecule and one solvent water molecule. The K+ ion is 7-coordinated by the oxygen atoms of two water molecules and by five oxygen atoms of four carboxylate groups, one of which is chelating. The extended structure can be described as a binodal network in which each K+ is a six-connected node, bonding to four carboxylate groups and two bridging water molecules, and the 2,2′-bipyridyl-5,5′-dicarboxylate linkers are eight-connected nodes, with each carboxylate group bridging four metal centers. Overall, this arrangement generates a complex network with point symbol {34.412.512}{34.44.54.63}2. Both of the bridging water molecules participate as donors in hydrogen-bonding interactions; one to solvent water molecules and a second to an oxygen atom of a carboxylate group.