Two new cadmium(II) coordination polymers based on bis(1,2,4-triazol-1-yl)alkane ligands and pyrazine-2,3-dicarboxylic acid.

Assemblies of pyrazine-2,3-dicarboxylic acid and Cd(II) in the presence of bis(1,2,4-triazol-1-yl)butane or bis(1,2,4-triazol-1-yl)ethane under ambient conditions yielded two new coordination polymers, namely poly[[tetraaqua[µ2-1,4-bis(1,2,4-triazol-1-yl)butane-κ(2)N(4):N(4')]bis(µ2-pyrazine-2,3-dicarboxylato-κ(3)N(1),O(2):O(3))dicadmium(II)] dihydrate], {[Cd2(C6H2N2O4)2(C8H12N6)(H2O)4]·2H2O}n, (I), and poly[[diaqua[µ2-1,2-bis(1,2,4-triazol-1-yl)ethane-κ(2)N(4):N(4')]bis(µ3-pyrazine-2,3-dicarboxylato-κ(4)N(1),O(2):O(3):O(3'))dicadmium(II)] dihydrate], {[Cd2(C6H2N2O4)2(C6H8N6)(H2O)2]·2H2O}n, (II). Complex (I) displays an interesting two-dimensional wave-like structure and forms a distinct extended three-dimensional supramolecular structure with the help of O-H...N and O-H...O hydrogen bonds. Complex (II) has a three-dimensional framework structure in which hydrogen bonds of the O-H...N and O-H...O types are found.

Diaqua-bis(N,N'-dibenzyl-ethane-1,2-diamine-κN,N')nickel(II) dichloride N,N-dimethyl-formamide solvate.

The asymmetric unit of the title complex, [Ni(C(16)H(20)N(2))(2)(H(2)O)(2)]Cl(2)·C(3)H(7)NO, consists of two Ni(II) atoms, each lying on an inversion center, two Cl anions, two N,N'-dibenzyl-ethane-1,2-diamine ligands, two coordinated water mol-ecules and one N,N-dimethyl-formamide solvent mol-ecule. Each Ni(II) atom is six-coordinated in a distorted octa-hedral coordination geometry, with the equatorial plane formed by four N atoms and the axial positions occupied by two water mol-ecules. The complex mol-ecules are linked into a chain along [001] by N-H⋯Cl, N-H⋯O and O-H⋯Cl hydrogen bonds. The C atoms and H atoms of the solvent mol-ecule are disordered over two sites in a ratio of 0.52 (2):0.48 (2).