Synthesis and Structural Characterization of a New Cadmium(II) Complex with a Double Betaine

A new flexible double betaine L (L = 1,4-bis(pyridinio-4-carboxylato-N-methyl)- benzene, C20H16N2O4) and its cadmium(II) complex [Cd(H2O)4L(NO3)]NO3?H2O 1 were synthe- sized. Complex 1 was obtained by self-assembly reaction of [Cd(NO3)2]?4H2O and L in hot water, and its crystal structure was determined by single-crystal X-ray diffraction analysis. Crystallo- graphic data for complex 1: C20H24CdN4O14?H2O, Mr = 674.85, monoclinic, space group P21/c, a = 13.7854(3), b = 14.2820(3), c = 14.9188(4) ?, β = 116.418(1)o, V = 2630.5(1) ?3, Z = 4, Dc = 1.704 g/cm3, μ(MoKα) = 0.911 mm-1, F(000) = 1368, the final R = 0.0315 and wR = 0.0768 for 3637 observed reflections with I > 2σ(I). In complex 1, L acts as a monodentate ligand to link a Cd(II) ion in a novel coordination mode of double betaines. The mononuclear [Cd(H2O)4L(NO3)] units are connected through intermolecular hydrogen bonds and π-π stacking reactions to generate a 3D network.