Nickel(II) coordination polymers-4,4′-bipyridine-connected six- and four-fold metal-succinate helices and their corresponding chiral and achiral networks

Abstract

The reaction of equimolar amounts of Ni(NO3)2· 6H2O, Na2(suc)·6H2O (suc = succinate) and 4,4′-bipyridine (bipy) under different conditions yield the coordination polymers [Ni(suc)(bipy)(H2O)2] n·2nH2O (1) and [Ni(suc)(bipy)(H2O) 2]n·nH2O (2). The complexes were characterized by elemental analysis, spectroscopic, thermogravimetric, and magnetic susceptibility measurements. Crystal structures reveal that the metal centers in both complexes are in a distorted octahedral N2O 4 coordination sphere assembled by mutually trans pairs of 4,4′-bipyridine, succinate, and water molecules. The helical metal-succinate chains have a right-handed sixfold configuration in 1, with guest water molecules inside the helix, and both right- and left-handed fourfold configurations in 2, with guest water molecules outside the helix. The parallel helical substructures are connected by 4,4′-bipyridine and provide 3D chiral 75.9 and achiral 65.8 networks in 1 and 2, respectively. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.