Hakan Erer

Supramolecular architectures of cadmium(II)-orotate complexes containing water clusters

Three novel cadmium(II) complexes containing orotate ligand have been synthesized under different pH and characterized by X-ray crystallography, IR spectroscopy and thermal analyses measurements. In the complexes, the orotate ligand exhibits three different coordination modes. In [Cd2(μ-HOr)2(H2O)4(NH3)2]·2H2O (1), the orotate acts as a tridentate ligand, showing unprecedented coordination mode. The (NH4)2[Cd3(μ-HOr)2(HOr)2(H2O)8]·4H2O (2) is constructed from orotate acting as both bidentate and tridentate bridging ligands. The Cd1 and Cd2 ions have two different coordination environments with four HOr, eight aqua ligands. Furthermore, 2 exhibits the novel 2D metal–water cluster layers. The (Hcha)4[Cd(HOr)2(H2O)(cha)][Cd(HOr)2(H2O)2]·H2O (3) (cha = cyclohexylamine, H3Or = orotic acid) consists of discrete cis and trans anionic complexes. The cha molecules exhibit chemically different functions by coordinating to Cd(II) ion in one form and being protonated and acting as counter–ions in other form. In the complexes, the supramolecular networks are constructed by novel N–H⋯O strong hydrogen bonds to form DA:AD motif, CO⋯π and π⋯π interactions.

Synthesis, spectral, thermal, and structural studies of copper(II)-squarate coordination polymer with 2-hydroxyethylpyridine, {[Cu(μ-sq)(etpy)2] · H2O} n

Polynuclear Cu(II)-squarate complex with 2-hydroxyethylpyridine, {[Cu(μ-sq)(etpy)2] · H2O} n has been prepared and characterized by elemental analysis, magnetic susceptibility, thermal analysis, IR, and UV-Vis spectroscopic studies (H2sq = squaric acid and etpy = 2-hydroxyethylpyridine). The structure of the complex was determined by single crystal X-ray diffraction. Density functional theory (DFT) and Hartree–Fock (HF) calculations were performed using the GAUSSIAN 03 program. The complex crystallizes in the monoclinic system, space group P21/c. The structure contains chains of squarato-O 1,O 3-bridged polynuclear copper(II) units held together by intermolecular hydrogen bonds, weak π–π and van der Waals interactions. The distorted octahedral geometry of Cu(II) is completed by two neutral bidentate etpy ligands through the nitrogen of pyridine and hydroxyl O atom. Thermal decomposition of the complex is studied from 30 to 500°C in a static air atmosphere.

Diaqua­bis(1,3-propane­diamine)nickel(II) squarate tetrahydrate

The asymmetric unit of the title compound, [Ni(C3H10N2)2(H2O)2](C4O4)·4H2O, contains one-half of the diaquabis(1,3-propanediamine)nickel(II) cation, one-half of the centrosymmetric squarate anion and two uncoordinated water molecules. In the cation, the NiII atom is located on a crystallographic inversion centre and has a slightly distorted octahedral coordination geometry. The six-membered chelate ring adopts a chair conformation. O—H⋯O hydrogen bonds link the cation and anion through the water molecule, while N—H⋯O hydrogen bonds link the cation and anion and cation and water molecules. In the crystal structure, intermolecular O—H⋯O and N—H⋯O hydrogen bonds link the molecules into a three-dimensional network structure.

Tris(ethyl­enediamine)­nickel(II) 1H-pyrazole-3,5-dicarboxyl­ate 1.67-hydrate

The asymmetric unit of the title compound, [Ni(C2H8N2)3](C5H2N2O4)·1.67H2O, consists of three [Ni(en)3]2+ dications (en is ethylenediamine), three [(pzdc)3]2− dianions (pzdc is pyrazole-3,5-dicarboxylate) and five water molecules. In each complex dication, the NiII atom is coordinated by six N atoms from three en ligands forming a distorted octahedral coordination geometry. In the crystal, the ions and water molecules are linked into a three-dimensional framework by a large number of N—H⋯O and O—H⋯O hydrogen bonds.