Synthesis,IR Spectrum,Thermal Analysis,and Crystal Structure of the Cyano‐bridged Heteronuclear Polymeric Complex: [Zn(teta)Ni(μ‐CN)2(CN)2]n

The heteronuclear polymeric complex, [Zn(teta)Ni(μ‐CN)₂(CN)₂]_n (teta: triethylenetetramine), was synthesized and characterized by elementel analysis, FT‐IR spectroscopy, thermal analysis and single crystal X–ray diffraction techniques. The complex crystallizes in the monoclinic system, space group P2₁/c and in which the Zn^II ion exhibits a distorted octahedral coordination by one tetradentate teta ligand and two bridging cyano groups as a trans position, whereas the Ni^II ion has square planer coordination and is coordinated by four cyano ligands. The decomposition reaction takes places in the temperature range 30–600 °C in the static air atmosphere.     

Syntheses,Spectra, Thermal Studies and Crystal Structures of Vitamin B13 Complexes of Nickel(II) with N,N,N′,N′‐Tetramethylethylenediamine and 2,2‐Dimethylpropane‐1,3‐diamine

Two nickel(II) complexes of vitamin B13 (H₃Or) with N,N,N′,N′‐tetramethylethylenediamine (tmen) and 2,2‐dimethylpropane‐1,3‐diamine (dmpen) were synthesized and characterized by means of elemental and thermal analyses, magnetic susceptibility, and IR and UV/Vis spectroscopic studies. The crystal structures of mer‐[Ni(HOr)(H₂O)₂(tmen)] · H₂O ( 1 ) and [Ni(HOr)(dmpen)₂] ( 2 ) were determined by using single‐crystal X‐ray diffraction. In the complexes, which crystallize in the triclinic system (space group for 1 ) and the monoclinic system (space group P2₁/c for 2 ), the Ni^II ions exhibit a distorted octahedral coordination. Ni^II ions are chelated by the deprotonated nitrogen atom of the pyrimidine ring and the oxygen atom of the carboxylate group, the distorted octahedral coordination completed by one tmen and two aqua ligands for 1 or two dmpen ligands for 2 .     

Synthesis, characterization and biological evaluation of a novel Cu(II) complex with the mixed ligands 2,6-pyridinedicarboxylic acid and 2-aminopyridine

A novel bridged binuclear Cu(II) complex with mixed ligands, di-μ-(2-aminopyridine(N,N′))-bis[(2,6-pyridinedicarboxylate)aquacopper(II)] tetrahydrate, formulated as [Cu(μ-ap)(dipic)(H₂O)]₂·4H₂O (1) (dipic = 2,6-pyridinedicarboxylate, ap = 2-aminopyridine), has been synthesized and characterized by elemental, spectral (IR and UV–Vis.), thermal analysis, magnetic measurements and single crystal X-ray diffraction analysis. The central Cu(II) ion resides on a centre of symmetry in a distorted square-pyramid coordination environment comprising of two N atoms, one from dipic and one from the ap ring, two carboxylate O atoms from dipic, and one O atom from water. Intermolecular N–HO and O–HO hydrogen bonds and π–π stacking interactions seem to be effective in the stabilization of the crystal structure. The free ligands and the complex were also evaluated for their antimicrobial and radical scavenging activities (DPPH = 1,1-diphenyl-2-picrylhydrazyl hydrate) using in vitro microdilution methods. Antimicrobial screening of the free ligands and their complex showed that the free ligands and the complex possess antifungal activity against Candida sp.     

Two-dimensional supramolecular networks generated from weak AgCpy interactions: Synthesis, structural, thermal and fluorescence studies of silver(I) complexes of 5,5-diethylbarbiturato with pyridine-2-ylmethanol and 2,6-dimethoxypyridine

Two new silver(I) complexes [Ag(barb)(pym)]·H₂O (1) and [Ag(barb)(dmpy)]·1.5H₂O (2) (barb = 5,5-diethylbarbiturate, pym = pyridine-2-ylmethanol and dmpy = 2,6-dimethoxypyridine) have been synthesized and characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. In both complexes, the silver(I) ions are linearly coordinated by the N atoms of a barb anion and a pym or a dmpy ligand, forming mononuclear species. The molecules of 1 and 2 are doubly bridged by N–HO hydrogen bonds involving the barb moieties and these hydrogen-bonded dimers are assembled into two-dimensional layered networks through weak AgC_py (η¹) interactions of ca. 3.3 Å. Additionally, the thermal and fluorescent properties of these complexes are also investigated.     

MHD mixed convection of a viscous dissipating fluid about a permeable vertical flat plate

The problem of steady laminar magnetohydrodynamic (MHD) mixed convection heat transfer about a vertical plate is studied numerically, taking into account the effects of Ohmic heating and viscous dissipation. A uniform magnetic field is applied perpendicular to the plate. The resulting governing equations are transformed into the non-similar boundary layer equations and solved using the Keller box method. Both the aiding-buoyancy mode and the opposing-buoyancy mode of the mixed convection are examined. The velocity and temperature profiles as well as the local skin friction and local heat transfer parameters are determined for different values of the governing parameters, mainly the magnetic parameter, the Richardson number, the Eckert number and the suction/injection parameter, f_w. For some specific values of the governing parameters, the results agree very well with those available in the literature. Generally, it is determined that the local skin friction coefficient and the local heat transfer coefficient increase owing to suction of fluid, increasing the Richardson number, Ri (i.e. the mixed convection parameter) or decreasing the Eckert number. This trend reverses for blowing of fluid and decreasing the Richardson number or decreasing the Eckert number. It is disclosed that the value of Ri determines the effect of the magnetic parameter on the momentum and heat transfer.     

Determination of cyanide,thiocyanate, cyanate,hexavalent chromium,and metal cyanide complexes in various mixtures by ion chromatography with conductivity detection

The first aim of this study was to develop a selective, sensitive, and reliable method for direct simultaneous determination of cyanate, thiocyanate, and hexavalent chromium by ion chromatography (IC) with conductivity detection. The other target was to successfully determine cyanides by utilizing same chromatographic system. Yet, since cyanides can not be detected by the direct method, free cyanide ions were converted into cyanate with chloramine-T at alkaline pH. In addition, strongly complexed metal cyanides were converted into cyanate by using photo-oxidation following chloramine-T. Total cyanate ion obtained from developed methods were analyzed with IC. The chromatographic separations on anion exchange column were accomplished by optimized multistep gradient eluent program using NaOH as the eluent. Proposed method was applied for the simultaneous determination of cyanide and hexavalent chromium in electroplating bath solutions and in industrial wastewater. Cyanide and hexavalent chromium could be measured in the linear dynamic ranges of 0.6–961.5 and 0.9–118.5 µmol L^?1, respectively. The limit of detection and limit of quantification of cyanide were 0.18 and 0.61 µmol L^?1, and these values for chromium(VI) were 0.26 and 0.86 µmol L^?1, respectively.     

A mononuclear, mixed (salicylato) (nicotinamide) complex of Zn(II) with penta- and hexa-coordination sites: a novel framework structure

The title compound, diaqua(bissalicylato-??O)(bisnicotinamide-??N)zinc(II)][bis(triaqua (monosalicylato-??O)(mononicotinamide-??N)zinc(II)salicylate, includes three Zn(II) ions, four nicotinamide ligands, six salicylate ligands and eight coordinated aqua ligands in the asymmetric unit in complex structure. The geometry around one of the Zn(II) ions is a slightly distorted octahedron, of which the equatorial plane is formed by two carboxylate oxygens and two aqua oxygens, while the axial positions are occupied by two pyridyl nitrogen atoms. The other Zn(II) ions adopt fivefold coordinations with one carboxylate oxygen atom from salicylate ligand, one N atom from nicotinamide ligand and three oxygen atoms from aqua ligands. In addition, there are two salicylate anions in the unit cell that are not coordinated. They provide charge balance as counter-ions in the complex framework.     

C−H?Pd interactions and cyano-bridged heteronuclear polymeric complexes

Three new heterometallic complexes, [Cu(N-Meim)₄Pd(μ-CN)₂(CN)₂]_n (1), [Zn(N-Meim)₃Pd(μ-CN)₂(CN)₂]_n (2) and [Cd(N-Meim)₂Pd(μ-CN)₄]_n (3), have been isolated from the reactions of M[Pd(CN)₄] (M = Cu(II), Zn(II) or Cd(II)) and N-Meim (N-methylimidazole) with in different molar ratios. All complexes have been characterized by X-ray analyses, vibrational (FT-IR and Raman) spectra, thermal and elemental analyses. The crystallographic analysis reveals that the crystal structures of 1 and 2 are 1D coordination polymer, while 3 presents a 2D network. In the Cu(II) and Zn(II) complexes, two cyanide groups of [Pd(CN)₄]²⁻ coordinated to the adjacent M(II) ions and distorted octahedral and square pyramidal geometries of complexes are completed by four and three nitrogen atoms of N-Meim ligands, respectively. The Cd(II) ion is six-coordinate, completed with the two nitrogen atoms of N-Meim ligands in the axial positions and the four nitrogen atoms from bridging cyano groups in the equatorial plane. The most striking features of complexes 1-3 are the presence of obvious C-H?Pd hydrogen-bonding interactions between the Pd(II) and hydrogen atoms of N-Meim ligand. This weak hydrogen bonding plays a crucial role in the architecture of the network polymers. The adjacent chains are held together by C-H?Pd, C-H?π or π?π interactions, forming three-dimensional network.     

Hydrogen Bonded Supramolecular Network from a Mixed Valence Cobalt System: Synthesis and Crystal Structure of [Co(H2O)6][Co(pydc)2(en)]2·14H2O

Abstract  

The [Co(H₂O)₆][Co(pydc)₂(en)]₂·14H₂O (1) compound (H₂pydc = Pyridine-2,3-dicarboxylic acid and en = ethylenediamine) was synthesized and characterized by elemental analysis, magnetic and spectroscopic measurements (UV–Vis and IR spectra) and single crystal X-ray diffraction technique. There are two coordination spheres with different charges inside this aqueous compound of ionic character. The cationic part is composed of Co(II) encircled by six aqua ligand. Whereas the anionic part contains two anions complex unit each with −1 charge and have Co(III) ions in the centre. As a result different coordination spheres have cobalt ions with different states. The crystallographic analysis revealed that 1 consists of both discrete one-cationic and two-anionic entities, [Co(H₂O)₆]²⁺ and [Co(pydc)₂(en)]₂⁻ and fourteen crystal water molecules. Two water molecules within the water cluster act as hydrogen-bonding acceptors, whereas one water molecule acts as a hydrogen-bonding donor to form a discrete water trimer. These water molecules have stabilized the crystal structure by strong hydrogen bonding interactions.