Syntheses, crystal structures and properties of a series of 3D cadmium coordination polymers with different topologies

Hydrothermal reactions of 2-, 3-, 4-cyanopyridine, NaN3 with CdCl2 in basified solvents yielded three coordination polymers [Cd3(2-pytta)2(N3)4(H2O)2]n (1), [Cd(3-pytta)2]n (2), [Cd3(4-pytta)2(N3)2Cl2(H2O)4]n (3). A similar reaction of tetrazole as ligand and the CdCl2 being replaced by CdI2 resulted in polymer [Cd2(tta)3I]n (4). X-ray single crystal structural analyses revealed that four compounds all show three-dimensional architectures. Complex 1 exhibits rare 3,4,4-connected 3-nodal with (3.92)2(3.94.10)(32.93.10) network in the Schäfli notation, while complex 2 is an anatase net with 3,6-connected (42.6)2(44.62.88.10) network. Complex 3 is 3,3,4,4-connected 4-nodal network with (4.102)2(42.104)(42.6.102.12)2(42.6)2 topology, and complex 4 can be simplified as an interesting alpha-Po network. The solid emission spectra of 1, 2, 3 and 4 have also been studied. From the results, it can be found complex 4 exhibits a long triplet lifetime that is unusual in CdII complexes.