Syntheses, characterization and crystal structures of eight Cd(II) carboxylates containing 3,5-dimethylpyrazole

Eight new complexes, namely [Cd(Hdmpz)2(L1)(2)0.5H(2)O](2) (1) (Hdmpz = 3,5-dimethylpyrazole, Ll = trichloroacetate), [Cd(Hdmpz)(2)(12)(2).H2O (2) (L2 = indole-3-acetate), Cd(Hdmpz)(2)(L3)(2) (3) (L-3 = 4-methylbenzoate), Cd(Hdmpz)(4)(L4)(2) (4) (L4 = 3-methylbenzoate), Cd(Hdmpz)(4)(L5)(2) (5) (L5 = 4-methoxybenzoate), Cd(Hdmpz)2(L6)(2) (6) (L-6 = 2-chloronicotinate), Cd(Hdmpz)(HL7)(2) (7) (HL7 = 2-hydroxy-5-(phenyldiazenyl)benzoate) and [Cd-2(Hdmpz)(6)(L8)(2)](Hdmpz)(2) (8) (L8 = o-phthalate) have been prepared by the self-assembly of Cd ions, 3,5-dimethylpyrazole and carboxylic acids at room temperature. All the complexes were characterized by elemental analysis, IR spectra, TG and single crystal X-ray diffraction analysis. The X-ray studies revealed that these complexes display mononuclear to dinudear structures, with an octahedral geometry around each cadmium ion. The 3,5-dimethylpyrazole ligand in all the compounds is coordinated only in a monodentate fashion by its neutral N group. In 2, 3 and 6, the carboxylate groups behave as chelating bidentate ligands. In 4 and 5, the carboxylate groups act as monodentate ligands. The COO- group in I is coordinated to the Cd centre in both monodentate and bridging bidentate modes. The carboxylates in 7 coordinate to the Cd centre in tridentate chelating bridging and bidentate bridging fashions, simultaneously, while in 8 there exists a tridentate bridging carboxylate ligand. Based on the X-ray crystallographic study, extensive intra- and intermolecular non-covalent interactions, such as classical hydrogen bonds, CH-CI, CH3-Cl, Cl. ...Cl, Cl...O, CH-N, CH3-N, C-H...O, CH3-O, C-H...pi, CH2...pi, CH3-pi and ir-it interactions, are analyzed. These compounds display different structures, such as a OD discrete mononuclear arrangement, sheet, 3D network, and 3D layer network. The thermal stabilities for 1-8 were examined and the results show that the complexes display good thermal stability. (c) 2014 Elsevier Ltd. All rights reserved.