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Five coordination polymers catena-[(3-Hampy)2[Zn7(N3)16(3-ampy)4]·3H2O] (1), catena-[Zn2(μ2-4-HO-py)(μ1,1-N3)4]·H2O (2), catena-[Zn2(μ2-4-amtz)(μ1,1-N3)4] (3), catena-[Zn(5-Et-2-Me-py)(μ1,1-N3)2] (4) and catena-[Zn(μ2-2-O-py-N-oxide)(μ1,1-N3)] (5), where 3-ampy = 3-aminopyridine, 4-HOpy = 4-hydroxypyridine, 4-amtz = 4-amino-4H-1,2,4-triazole, 5-Et-2-Mepy = 5-ethyl-2-methylpyridine and 2-HO-py-N-oxide = 2-hydroxypyridine-N-oxide were synthesized and structurally characterized by single crystal X-ray crystallography. The complexes display different dimensionality depending on the nature of the coligand. The anionic polymer in complex 1 consists of 1D system of defective dicubanes with two different azido-bridging μ1,1-N3 and μ1,1,1-N3 modes. Complexes 2 and 3 are isostructural and both exhibit 2D networks with μ(O,O)-pyridinone bridging molecule in 2 or μ(N,N′)-bridging 4-amtz in 3, and μ1,1,-azide bridging. Complex 4 reveals a zigzag chains of 1D polyhedral through a doubly bridged μ1,1-N3 bonding mode, whereas in complex 5 a 1D polymeric chain is generated via singly bridged μ1,1-N3 bonding and hydrogen bonding results in the formation of supramolecular 2D system. The emission spectral properties of the parent free ligands and their corresponding Zn(II) complexes were investigated where enhancement luminescence emissions with strong red shifts were observed in complexes 2, 4 and 5.

Three new metal (II) complexes namely [Mn(3-ampy)4(N3)2] (1), [Cd(3-ampy)(H2O)4]n(SO4)n · (H2O)n (2) and [Cd(3-ampy)(N3)2]n (3) (3-ampy = 3-aminopyridine), have been synthesized and characterized by spectroscopic and crystallographic methods. The structure of 1 contains distorted octahedral Mn (II) atoms, monodentate 3-ampy and azide ligands. The structure of 2 consists of a packing of [Cd(3-ampy)(H2O)4]2+ cations and SO 4 2 - anions and lattice water molecules. The Cd(1) center in the cation is coordinated by four O atoms from aqua molecules [Cd–O from 2.261(3) to 2.409(2) A] and two N atoms; the hetero nitrogen atoms of 3-ampy [Cd–N 2.262(3) A], whereas Cd(2) atom is surrounded by four aqua molecules and two nitrogen atoms of two amino groups of 3-ampy molecules [Cd–N 2.378(3) A]. 3-Aminopyridine, therefore, acts as bidentate bridging ligands generating a 1D chain along [0, 1, −1]. Different hydrogen bonds are formed extending the structure to a 3D network. Complex 3 contains dimeric units Cd2N2 through double μ-1,1 azide bridges, N,N′-3-ampy ligand and μ-1,3 azides generating a 3D network structure. There are hydrogen bonds of the type N–H⋯N between the NH2 and azido groups consolidating the structure. The thermal properties of the three complexes have been recorded and discussed.

Three metal complexes with the 5-(4-pyridyl)tetrazolate anion, (4-PTZ)−, as ligand were obtained by the reaction of 4-cyanopyridine with corresponding metal azides in aqueous solution. Isomorphic complexes of composition [M(4-PTZ)2(H2O)4] · 2H2O with M=Mn(II) (1) and Cd(II) (2) were obtained, whereas [Ca1.5((4-PTZ)2H)(N3)2(H2O)5](H2O)0.3 (3) was separated from calcium azide solutions. The IR spectra and the thermal behaviour of the complexes are measured and discussed. The single crystal X-ray diffraction revealed that the isomorphous structures of 1 and 2 consist of octahedrally coordinated metal centers, where two 4-PTZ anions act as monodentate ligands via their pyridine-N atoms in trans-positions. The structures also contain six water molecules, four act as monodentate ligands and the remaining two as lattice water molecules. Hydrogen bonds of the types O–H…O and O–H…N connect the mononuclear units to a three-dimensional network structure. The chain structure of complex 3 features octahedrally coordinated Ca(1); dinuclear subunits of pentagonal-bipyramidal Ca(2) centers; azide groups acting in end-on and end-to-end bridging mode; a (4-PTZ)2H ligand in its zwitter ionic form coordinated via N(1) atom of the tetrazole ring to Ca(2), as well as lattice and ligand water molecules. Again, a complicated hydrogen bond system connects the chains of polyhedra to form a 3-D network structure.

Three new cadmium(II) complexes: [Cd(4-Clpy)2(NCS)2]n (1), [Cd(3-aldpy)(H2O)(N3)2]n (2) and [Cd(3-CNpy)(N3)2]n (3) (4Clpy ¼ 4-chloropyridine, 3-aldpy ¼ 3-aldehyde-pyridine, and 3-CNpy ¼ 3-cyanopyridine) have been synthesized and structurally characterized. The IR spectra of the complexes are measured and discussed. The single crystal X-ray diffraction revealed that the structure of 1 features l-1,3-thiocyanate bridges and 1D chains. It consists of alternate octahedrally coordinated Cd atoms. Both Cd(1) and Cd(2) are surrounded by pairs of 4-Clpy, S atoms and N atoms of two di-l-1,3 thiocyanato bridges in trans and cis arrangements, respectively. In complex 2 each octahedrally coordinated Cd binds two di-l-1,1 azide bridges in a zigzag 1D chain and the other two positions are occupied by O and N atoms from aqua and 3-aldpy molecules, respectively. Hydrogen bonds of the types O–H ��� O and O–H �� � N are formed between aqua molecules and end nitrogen atoms of the l-1,1 azide bridges generating 3D framework structure of 2. The structure of 3 consists of [Cd(N3)2]n chains in which each octahedrally coordinated Cd atom is linked by two di-l-1,1 azide bridges. These chains are cross-linked by l-N ; N 0 -3-CNpy bridges generating 2D systems for this complex.

Two new polymeric cadmium(II) complexes; [Cd(3,5-DMP)2(N3)2] (1) and [Cd(4-Brpy)2(NCS)2] (2), where 3,5-DMP=3,5-dimethylpyridine and 4-Brpy=4-bromopyridine, have been synthesized and characterized. IR spectral data suggest end-to-end bridging azido and thiocyanato ligands. X-ray crystal structure determination has shown the 1-D complex 1 to contain each cadmium octahedrally coordinated by two double μ(1,3)-bridging azides and the other two sites are occupied by two pyridine ligands in a cis-arrangement. The CdCd distances in the Cd2(N3)2 eight membered rings are 5.142(2) and 5.152(2) A, the azide ligands are almost symmetrical and linear [NN distances: 1.167(5)–1.182(5) A; ∠NNN=176.7(4)° and 177.6(4)°]. In complex 2 each octahedrally cadmium atom is coordinated by two trans pyridine ligands and two trans nitrogen or sulfur atoms from four μ(N,S) bridging thiocyanato groups. The other end atoms of these four thiocyanato ligands bind four different cadmium atoms giving a 2-D layer structure.