The Solvent Effect on Composition and Dimensionality of Mercury(II) Complexes with Picolinic Acid

Three new mercury(II) coordination compounds, {[HgCl(pic)]}_n (1), [HgCl(pic)(picH)] (2), and [HgBr(pic)(picH)] (3) (picH = pyridine-2-carboxylic acid, picolinic acid) were prepared by reactions of the corresponding mercury(II) halides and picolinic acid in an aqueous (1) or alcohol–methanol or ethanol (2 and 3) solutions. Two different types of coordination compounds were obtained depending on the solvent used. The crystal structures were determined by the single-crystal X-ray structural analysis. Compound 1 is a one-dimensional (1-D) coordination polymer with mercury(II) ions bridged by chelating and bridging N,O,O′-picolinate ions. Each mercury(II) ion is four-coordinated with a bidentate picolinate ion, a carboxylate O atom from the symmetry-related picolinate ion and with a chloride ion; the resulting coordination environment can be described as a highly distorted tetrahedron. Compounds 2 and 3 are isostructural mononuclear coordination compounds, each mercury(II) ion being coordinated with the respective halide ion, N,O-bidentate picolinate ion, and N,O-bidentate picolinic acid in a highly distorted square-pyramidal coordination environment. Compounds 1–3 were characterized by IR spectroscopy, PXRD, and thermal methods (TGA/DSC) in the solid state and by ¹H and ¹³C NMR spectroscopy in the DMSO solution.

Hydrogen-Bonded Frameworks of Mercury(II) Complexes with Pyridinedicarboxylic Acids

Three novel mercury(ii) coordination compounds, [HgCl(2,4-pydcH2)(2,4-pydcH)]·2H2O (1) and [HgCl(2,6-pydcH)(H2O)]·3H2O (2) that exhibit hydrogen-bonded 3D frameworks, and [Hg(2,6-pydcH)2]·2H2O (3), exhibiting only hydrogen-bonded 1D chains (2,4-pydcH2 = pyridine-2,4-dicarboxylic acid; 2,6-pydcH2 = pyridine-2,6-dicarboxylic acid), were prepared in the reactions of the corresponding pyridinedicarboxylic acid with mercury(ii) chloride or mercury(ii) acetate. Compounds 1–3 were prepared by conventional solution synthesis. Only the hydrogen-bonded 1D chain of 3 was robust enough to be prepared by mechanochemical synthesis. The crystal structures of 1–3 were determined by the single-crystal X-ray diffraction method. Neutral 2,4-pydcH2 and partially deprotonated 2,4-pydcH− act as N,O-bidentate ligands in the structure of 1 whereas crystal structure analysis reveals O,N,O′-tridentate 2,6-pydcH− ligand in the structures of 2 and 3. Compounds 1–3 were characterised by IR spectroscopy in the solid state, and compounds 1 and 2 were also characterised by 1H and 13C NMR spectroscopy in DMSO solution. Thermal properties of 1–3 were also investigated. NMR data support a collapse of the hydrogen-bonded frameworks of 1 and 2 in DMSO solution, and the existence of monomeric species in DMSO solutions.

DFT study and crystal structure analysis of a new nano-structure five coordinated Hg(II) complex involving C-H⋯O, N⋯O and π⋯π interactions in a supra-molecular structure

In this research, template synthesis and crystal structure of a new HgLI₂ complex are presented (L=N(1)-(4-nitrobenzylidene)-N(2)-(2-((E)-(4-nitrobenzylidene)amino)ethyl)ethane-1,2-diamine). The mercury complex crystallizes in the triclinic system with space group of P1¯. The crystal structure of the complex shows a distorted trigonal bipyramidal geometry around the mercury(II) center; including two I and an N atoms of Schiff base ligand in equatorial plane and two iminic N atoms in axial positions. Two five membered mercury containing rings [Hg(-N-C-C-N-)] are found in the structure. Some C-H⋯O, N⋯O and π⋯π intermolecular interactions causes a supra-molecular network in the solid-state. In addition to crystal structure analysis, density functional theory (DFT) study at the B3LYP/LanL2DZ level of theory has been also performed on the structure. Thereafter some theoretical structural and spectral data were compared with experimental results. Furthermore, total energy levels of HOMO and LUMO orbitals, molecular electrostatic potential, Mullikan atomic charges, thermodynamic and polarizability properties of the complex were calculated. Finally the mercury complex was prepared in nano-structure size confirmed by SEM and XRD analyses. The particles size of the titled complex was evaluated under 40 nm based on Sherrer's formula.

Synthesis, structural investigations and corrosion inhibition studies on Mn(ii), Co(ii), Ni(ii), Cu(ii) and Zn(ii) complexes with 2-amino-benzoic acid (phenyl-pyridin-2-yl-methylene)-hydrazide

Metal complexes of 2-amino-benzoic acid (phenyl-pyridin-2-yl-methylene)-hydrazide are synthesized and the structures are determined by X-ray crystallography. These compounds show appreciable corrosion inhibition efficiency for mild steel in 1 M HCl.

A novel alkaline earth strontium(II) coordination polymer: poly[hexaaquatetrakis(μ5-pyridine-2,6-dicarboxylato)bis(μ4-pyridine-2,6-dicarboxylato)(μ7-sulfato)heptastrontium(II)]

The title compound, [Sr7(C7H3NO4)6(SO4)(H2O)6]n, has been synthesized by an ionothermal method using the ionic liquid 1-ethyl-3-methylimidazolium ([Emim]Br) as solvent, and characterized by elemental analysis, energy-dispersive X-ray spectroscopy, IR and single-crystal X-ray diffraction. The structure of the compound can be viewed as a three-dimensional coordination polymer composed of Sr(2+) cations, pyridine-2,6-dicarboxylate anions, sulfate anions and water molecules. The compound not only exhibits a three-dimensional structure with a unique coordination mode of the sulfate anion, but also features the first example of a heptanuclear strontium(II) coordination polymer. The structure is further stabilized by O-H···O hydrogen bonds and π-π stacking interactions.

A series of divalent metal coordination polymers based on isomeric tetracarboxylic acids: synthesis, structures and magnetic properties

A series of M(ii) coordination polymers has been synthesized. 1–3 contain 1D infinite chains, and these 1D chains are further linked by hydrogen bonding to form 3D supramolecular networks. While 4 and 5 show tetra- or penta-nodal 3D network, respectively.