Synchrotron study of poly[[di- aqua-(-2,2′-bipyridyl-5,5′- dicarboxyl-ato)di-potassium] dihydrate]

Abstract

The title compound, {[K2(C12H6N2O4)(H 2O)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′- dicarboxyl-ate ligand, one coordinated water mol-ecule and one solvent water mol-ecule. The K+ ion is 7-coordinated by the oxygen atoms of two water mol-ecules and by five oxygen atoms of four carboxyl-ate 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 carboxyl-ate groups and two bridging water mol-ecules, and the 2,2′-bipyridyl-5,5′-dicarboxyl-ate linkers are eight-connected nodes, with each carboxyl-ate group bridging four metal centers. Overall, this arrangement generates a complex network with point symbol {34.4 12.512}{34.44.54.6 3}2. Both of the bridging water mol-ecules participate as donors in hydrogen-bonding inter-actions; one to solvent water mol-ecules and a second to an oxygen atom of a carboxyl-ate group.