Syntheses and characterizations of one-dimensional coordination polymers generated from cadmium nitrate and bipyridine ligands

Two new one-dimensional organic/inorganic composite polymers were synthesized by the reaction of Cd(NO3)(2). 4H(2)O with 1,2-bis(4-pyridyl)ethyne or trans-1,2-bis(4-pyridyl)ethene in several solvent systems. [Cd(NO3)(2)(1,2-bis(4-pyridyl)ethyne)(1.5)](n) (1), which has an infinite one-dimensional structure with interpenetrating molecular ladders, was obtained by reacting Cd(NO3)(2). 4H(2)O with 1,2-bis(4-pyridyl)ethyne in a methylene chloride/methanol solvent system. It crystallized in the monoclinic space group C2/c (No. 15), with a = 20.713(3) Angstrom, b = 17.450(2) Angstrom, c = 14.451(3) Angstrom, beta = 129.203(8)degrees, Z = 8. [Cd(NO3)(2)(1,1-bis(4-pyridyl)ethene)(1.5)](n) (2) was generated from the reaction of Cd(NO3)(2). 4H(2)O with the trans-1,2-bis(4-pyridyl)ethene ligand in an ethanol/water system. It has a novel infinite non-interpenetrating zigzag chain structure which is made up of trans-1,2-bis(4-pyridyl)ethene-Cd-trans-1,2-bis(4-pyridyl)ethene-Cd-tra building units. Compound 2 crystallized in the triclinic space group Pi (No. 2), with a = 10.725(2) Angstrom, b = 10.814(2) Angstrom, c = 9.517(2) Angstrom, alpha = 104.21(2)degrees, beta = 94.60(1)degrees, gamma = 106.62(1)degrees, Z = 2. In compound 1, the Cd(II) centers lie in a heptacoordinate environment, while in compound 2, the Cd(II) atoms adopt an octahedral geometry. The two kinds of polymer structures are based on a T-shape and a linear building block, respectively. [Cd(NO3)(2)(1,2-bis(4-pyridyl)ethane)(1.5)](n), (3) was also synthesized by the reaction of Cd(NO3)(2). 4H(2)O with the 1,2-bis(4-pyridyl)ethane ligand in a methylene chloride/methanol system. Polymer 3 farms square units, which are linked through the two Cd(II) centers to give infinite linear chains. The synthesis of compound 3 was reported by Fujita (Fujita, M. J. Chem. Sec., Chem. Commun. 1994, 1977) using a different solvent system.