Two- and three-dimensional cadmium coordination polymers based on N,N-(2-pyridyl)-(4-pyridylmethyl)amine

The synthesis of a bipyridine ligand with a flexible spacer and a noncoordi nating amine group N,N-(2-pyridyl)(4-pyridylmethyl)amine, L-2, and its coor dination chemistry with cadmium have been investigated. Two-dimensional (2D ) coordination polymers of L-2 with empirical formulas [Cd(L-2)(2)(ClO4)(2) ](infinity), 1, or [Cd(L-2)(2)(NO3)(2)](infinity), 2, were prepared by hydr o(solvo)thermal reactions of L-2 and Cd(ClO4)(2). 6H(2)O or Cd(NO3)(2). 4H( 2)O in mixtures of water and ethanol, respectively. Single-crystal X-ray di ffraction studies reveal that 1 and 2 have similar structures in which each L-2 ligand bridges two cadmium centers with both the 4-pyridyl and 2-pyrid yl nitrogen atoms to result in 2D rhombohedral polymeric grids. The two rin gs of L-2 are essentially perpendicular to each other, likely to accommodat e the coordination of both pyridyl nitrogen atoms to the Cd centers as well as the "intramolecular" hydrogen bonds between the amine group in the flex ible spacer and the coordinated anion group. When the hydro(solvo)thermal r eaction was carried out between L-2 and CdSO4. 6H(2)O, a 3D Cd coordination polymer [Cd-2(L-2)(4)(H2O)(2)(SO4)(2)](infinity), 3, resulted. Two distinc t Cd centers reside in the asymmetric unit in 3. One Cd center coordinates to four 4-pyridyl nitrogen atoms of L2 ligands and two sulfate groups, whil e the other Cd center binds to two 2-pyridyl nitrogen atoms, two sulfate gr oups, and two water molecules. The two distinct cadmium centers are bridged by both L-2 ligands and sulfate groups to result in an unusual 3D polymeri c structure. Crystal data for 1: monoclinic space group C2/c, a = 8.4931(6) Angstrom, b = 17.264(1) Angstrom, c = 16.699(1) Angstrom, beta = 99.517(6) degrees, V = 2559.4(1) Angstrom(3), Z = 4, R = 0.034, R-w = 0.039. Crystal data for 2: monoclinic space group C2/c, a = 8.6231(5) Angstrom, b = 17.288 (1) Angstrom, c = 16.1675(7) Angstrom, beta = 94.730(2)degrees, V = 2401.9( 1) Angstrom(3), Z = 4, R = 0.050, R-w = 0.058. Crystal data for 3: monoclin ic, space group P2(1)/n, a = 11.7188(2) Angstrom, b = 15.7525(3) Angstrom, c = 12.8528(1) Angstrom, beta = 93.064(1)degrees, V = 2369.2(1) Angstrom(3) , Z = 2, R = 0.042, R-w = 0.047.