Copper(II), zinc(II), and cadmium(II) coordination polymers with 2-methylglutarato and 4,4′-dipyridyldisulfide

Three new coordination polymers of copper(II), zinc(II) and cadmium(II), Cu(H₂O)(Dpds)(2-MGA) (I), [Zn(Dpds)(2-MGA)] · 1.25H₂O (II) and [Cd(H₂O)(Dpds)(2-MGA)] · 0.25H₂O (III) (Dpds = 4,4′-dipyridyldisulfide, H₂MGA = (RS)-2-methyl glutaric acid), have been synthesized and characteried by X-ray single crystal structure determination. The Cu atoms in I are alternately bridged by Dpds ligands and 2-methylglutarato ligands to generate 1D chain. The resulted chains are assembled via S...S weak interactions into 2D layers, which are through twofold 2D parallel/2D parallel mode inclined interpenetration to induce 3D supramolecular architecture. In II, the ZnN₂O₂ tetrahedras are bridged by 2-MGA anion and Dpds ligands to form 2D (4,4) networks, which are assembled via hydrogen bonds to 3D supramolecular architecture. The centrosymmetric binuclear units Cd₂(2-MGA)₂ in III are bridged by Dpds ligands to form 1D repeated rhomboids chains, which are interlinked via S...S weak interactions into 2D layer, and the resulting 2D sheets are inclined parallel into 3D network.     

Complexes of N-nicotinoyl-N′-2-furanthiocarbohydrazide with oxovanadium(IV), manganese(II), iron(II & III), cobalt(II), nickel(II), copper(II) and zinc(II)

A new potential tetradentate ligand, N-nicotinoyl-N-2-furanthiocarbohydrazide (H₂Nfth), and its complexes with VO^IV, Mn^II, Fe^II,III, Co^II, Ni^II, Cu^II and Zn^II have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, u.v.–vis, i.r., n.m.r., ES⁺ and FAB mass spectral data. The room temperature e.s.r spectra of the VO^IV and Fe^III complexes yield g values, characteristic of octahedral complexes. The Mössbauer spectra of [Fe(HNfth)₂] and [Fe₂(Nfth)₃] at room temperature and at 78 K suggest the presence of high-spin iron(II) and iron(III), respectively. The complexes are electrically insulating at room temperature, however, their conductivities increase as the temperature increases from 333–383 K, with a band gap of 0.46–0.77 eV, indicating their semiconducting behaviour. H₂Nfth and its soluble complexes have been screened against several bacteria and fungi.     

β-diketone complexes of manganese(II), cobalt(II), nickel(II) and palladium(II)

Summary The reactions of manganese(II), cobalt(II) and nickel(II) acetates (1 mole) with antipyrine-4-azo--ethylcyanoacetate (HL¹) and antipyrine-4-azo--acetylacetone (HL²) (1 mole) produce complexes of the M(L)₂ type. K₂PdCl₄ (1 mole) reacts with HL¹ and HL² (1 mole) to yield complexes of the general formula PdLCl, the ligands behaving as monobasic tridentates. The electronic spectral and magnetic data show the complexes to be high-spin octahedral, whereas the palladium(II) complexes are diamagnetic square planar. The complexes were characterized by elemental analyses, conductance measurements and i.r. and electronic spectra as well as magnetic susceptibility measurements and thermal (t.g.a. and d.t.a.) analysis.Nuclear Material Authority.     

Complexes of N-phenyl-N′-2-furanthiocarbohydrazide with oxovanadium(IV), manganese(III), iron(III), cobalt(II), nickel(II), copper(II) and zinc(II)

A new ligand, N-phenyl-N -2-furanthiocarbohydrazide (HPhfth), and its complexes with VO^IV, Mn^III, Fe^III, Co^II, Ni^II, Cu^II and Zn^II have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, i.r., n.m.r., u.v.–vis., mass and FAB mass spectral data. The room temperature e.s.r. spectra of the VO^IV, Fe^III and Cu^II complexes yield <g> values characteristic of square pyramidal VO^IV, octahedral Fe^III and square planar Cu^II, respectively. The Ni^II and Cu^II complexes semiconduct, but the Zn^II complex is an insulator at room temperature. However, the conductivity increases as the temperature increases from 303–383 K, with a band gap of 0.21–1.01 eV. HPhfth and its soluble complexes have been screened against several bacteria and fungi.     

Complexation between decamethyl-3,3′-bis(dipyrrolylmethene) and zinc(II), copper(II), and cobalt(II) acetates

Decamethyl-3,3′-bis(dipyrrolylmethene) dihydrobromide H₂L · 2HBr (H₂L is bis(3,4,7,8,9-pentamethylpyrrol-3-yl)methane), which is the simplest representative of a novel class of oligo(dipyrrolylmethenes) belonging to chromophore chelating nonmacrocyclic ligands, were examined by ¹H NMR, IR, and electronic absorption spectroscopy. Complexation reactions of H₂L · 2HBr with M(AcO)₂ (M = Zn(II), Cu(II), and Co(II)) in DMF at 298.15 K were monitored by electronic absorption spectroscopy and studied by the molar ratio method. The thermodynamic constants K ⁰ of these reactions were estimated. The d metal ions coordinate H₂L to give the binuclear homoleptic complexes [M₂L₂]. The reactions proceed through the intermediate binuclear heteroleptic complex [M₂L(AcO)₂] detected by spectroscopic methods. The thermodynamic stabilities of [M₂L₂] and [M₂L(AcO)₂] increase when moving from Cu(II) to Zn(II) and Co(II). The probability of formation and stability of [M₂L₂] containing 3,3′-bis(dipyrrolylmethene) are substantially higher than those of analogous complexes with the 2,2′-isomer (decamethyl-2,2′-biladienea, c). The low K ⁰ values for the complexation between H₂L and Cu(AcO)₂ are due to slow oxidation of the biladiene ligand into a bilatriene with participation of Cu²⁺ ions.     

Tetrameric complexes of germanium(IV) and cobalt(II), Nickel(II), or Zinc(II) with 1,3-Diamino-2-propanol-tetraacertic acid: crystal and molecular structures of [(OH)2Ge2(μ-Hpdta)2Zn2(H2O)4] · 12H2O

Heteronuclear germanium(IV) and Zn(II) (Co(II), Ni(II)) complexes with 1,3-diamino-2-propanol-tetraacetic acid (H₅Hpdta) were synthesized. The compounds were characterized by elemental analysis, thermogravimetry, and IR spectroscopy. X-ray diffraction analysis of the crystals of [(OH)₂Ge₂(??-Hpdta)₂Zn₂(H₂O)₄] · 12H₂O (I) was performed. The crystals are tetragonal, a = 15.2022(9)?, c = 20.932(3) ?, V = 4837.5(7) ?³, Z = 4, space group P4₃, R1 = 0.0449 over 11399 reflections with I > 2??(I). The structural units of the crystal are tetrametric complex molecules [(OH)₂Ge₂(??-Hpdta)₂Zn₂(H₂O)₄] and water molecules of crystallization. The tetramer is composed of two similar neutral dimeric molecules [(OH)Ge(??-Hpdta)Zn(H₂O)₂]. The germanium and zinc atoms in the dimer are linked by the bridging oxygen atom of the deprotonated isopropanol group of the Hpdta^5? ligand (average Ge-O, 1.844(2)?; Zn-O, 2.192(3)?). The coordination sphere of the Ge and Zn atoms contains also one nitrogen atom (average Ge-N, 2.074(4)?; Zn-N, 2.156(3)?), four oxygen atoms belonging to four acetate branches of the octadentate Hpdta^5? ligands including two carboxyl O atoms for each Ge atom (average Ge-O, 1.912(3)?) and two carbonyl O atoms for each Zn (average Zn-O, 2.065(3)?). The coordination polyhedron of each Ge atom is completed to a distorted octahedron by the oxygen atom of the terminal hydroxy group (average Ge-O, 1.772(2)?) and the carboxyl oxygen atom of the bridging acetate branch (average Ge-O, 1.926(3)?) coordinated through carbonyl oxygen to Zn atom (average Zn-O, 2.148(3)?) of the second dimeric molecule. The distorted octahedron around each Zn atom is completed by oxygens of two water molecules at substantially different distances (average Zn-O, 1.984(3) and 2.100(3)?). The structural units are combined by O-H??O hydrogen bonds to form a framework.     

Thermodynamics of Copper(II), Zinc(II), Cobalt(II), Mercury(II), and Nickel(II) Complexation with α,α-Dipyrrolylmethene in DMF

Thermodynamics of complexation reactions between Zn(II), Ni(II), Hg(II), Co(II), and Cu(II) acetates and 3,35,5-tetramethyl-4,4-dibutyldipyrrolylmethene in DMF at 298.15 K is studied by calorimetric and spectrophotometric methods. The replacement of Zn²⁺, Ni²⁺, and Hg²⁺ ions by Co²⁺ and Cu²⁺ ions was found to increase the equilibrium constants of reactions of complex formation with dipyrrolylmethene by more than two orders of magnitude. The role of solvation interactions in coordination of dipyrrolylmethene by d-metal ions is established.     

Copper(II), nickel(II), cobalt(II) and oxovanadium(IV) complexes of substituted β-hydroxyiminoanilides

Complexes of the general formula, ML₂ [M = Cu^II, Ni^II, Co^II and OV^IV; L = 1,2,3,5,6,7,8,8a-octahydro-3-hydroxyimino-N-(4-X-phenyl)-l-phenyl-5-(phenylmethylene)-2-naphthalenecarboxamide (X = H, Me, OMe, Cl)] have been prepared and characterized on the basis of elemental analysis, magnetic moments and i.r., e.p.r. and electronic spectra. These metal complexes contain the N₄ chromophore with the ligand coordinating through nitrogens of the azomethine and deprotonated anilide functions. C.v. measurements indicate that the copper(II) complexes are quasi-reversible in acetonitrile solution. Square planar and square pyramidal structures are assigned respectively to the copper(II) and oxovanadium(IV) complexes, whereas tetrahedral geometry is assigned to the nickel(II) and cobalt(II) complexes. Deprotonated anilide nitrogen is involved in coordination and the presence of an electron-donating group para to the anilide function decreases the ΔE values of the d–d transitions while the value is found to increase when electron-withdrawing groups are substituted. Line spacing in the e.p.r. spectra of the copper(II) and oxovanadium(IV) complexes increases when methyl group is para to the anilide group, and decreases when this group is replaced by methoxy or chloro. The ν(C–N) of the anilide group and the ν(C-N) of the azomethine function of the oxime metal complexes are metal-sensitive and the blue shift for the above stretching frequencies follows the order: copper(II) > oxovanadium(IV) > nickel(II) ≈ cobalt(II). This revised version was published online in June 2006 with corrections to the Cover Date.     

Preparation, spectral and thermal properties of Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) complexes with iodosubstituted 2,2′-dipyrrolylmethene

Complexes [ML₂] of cobalt(II), nickel(II), copper(II), zinc(II), and cadmium(II) with asymmetrically substituted (E)-3-ethyl-5-[(4-iodo-3,5-dimethyl-2H-pyrrol-2-ylidene)methyl]-2,4-dimethyl-1H-pyrrole (HL) have been prepared and characterized for the first time. The spectral properties, stability in solutions and in the solid phase at elevated temperature of the complexes have been studied. The effects of complexing metal ion and the reaction medium on the spectral luminescent properties (absorptivity, quantum yield, fluorescence lifetime, and the radiation constant) and on thermal destruction of the [ML₂] complexes have been discussed.     

Antimicrobial studies of N - N ′-dicarboxydiethyloxamide and its Co(II), Ni(II), Cu(II) and Zn(II) complexes

Neutral complexes of Cu(II), Ni(II), Co(II), and Zn(II) have been synthesized from the oxamide-based ligand derived from leucine and diethyloxalate. The structural features have been deduced from their microanalytical, IR, UV/Vis, mass, ¹H and ¹³C NMR spectral data. The Co(II) and Ni(II) chelates have octahedral geometries and the Cu(II) chelate is a square-pyramidal geometry. The non-electrolytic and monomeric nature of the complexes is shown by their magnetic susceptibility and low conductance data. The biological activities of the ligand and its metal chelates against gram-positive and negative bacteria and fungi are also reported. All the compounds are antimicrobially active and show higher activity than the free ligand.     

Potentiometric determination of the formation constants for complexes of 3,2′,2″-triaminopropyldiethylamine with cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II)

The tripodal tetraamine ligand N{(CH₂)₃NH₂}{(CH₂)₂NH₂}₂ (pee), has been investigated as an asymmetrical tetraamine chelating agent for Co^II, Ni^II, Cu^II, Zn^II and Cd^II. The protonation constants for this ligand and the formation constants for its complexes have been determined potentiometrically in 0.1 M KCl at 25 °C. The successive protonation constants (log K _n ) are: 10.22, 9.51, 8.78 and 1.60 (n = 1–4). One complex with formula M(pee)²⁺ (M = Co, Ni, Cu, Zn and Cd) is common to all five metal ions and the formation constant (log _ML) is: 12.15, 14.17, 16.55, 13.35 or 9.74, respectively. In addition to the simple complexes, Co^II, Cu^II and Zn^II also give hydroxo complexes, and Cu^II and Ni^II give complexes with monoprotonated pee. [Zn(pee)](ClO₄)₂ and [Cd(pee)Cl](ClO₄) complexes were isolated and are believed to have tetrahedral and trigonal-bipyramidal structures, respectively.     

Complexes of acetic acid α-(N-benzoxazolin-2-one) with Zn(II), Cu(II), and Co(II): Syntheses and crystal structures

The results of syntheses and X-ray diffraction analyses of mononuclear complexes [ML₂(H₂O)₄] (M = Co²⁺(I), Cu²⁺(II), and Zn²⁺(III)) containing water molecules and anions of acetic acid α-(N-benzoxazolin-2-one) (L = C₉H₆O₄) are presented. The crystals of complexes I–III are isostructural (space group P2₁/n, Z = 2) and are built of discrete neutral complex molecules. The crystallographic data are as follows: for complex I, a = 6.1470(5), b = 5.3310(3), c = 30.5894(17) Å, β = 95.056(6)°, V = 998.50(11) ų; for complex II, a = 5.9661(6) Å, b = 5.1414(4) Å, c = 32.672(2) Å, β = 92.395(6)°, V = 1001.33(14) ų; and for complex III, a = 6.1404(3) Å, b = 5.3476(2) Å, c = 30.5865(12) Å, β = 94.708(4)°, V = 1000.96(7) ų. The metal atoms (M) of the complexing agents are localized in the crystallographic symmetry centers and have a distorted octahedral environment due to two oxygen atoms of the carboxy groups of two monodentate ligands (L) and four water molecules. The M-O(1w)(H₂O) and M-O(2w)(H₂O) bond lengths for the indicated complexes are 2.088(3) and 2.118(3), 2.446(3) and 1.971(3), and 2.113(4) and 2.093(3) Å for M = Co²⁺, Cu²⁺, and Zn²⁺, respectively. The crystal structures are formed due to packing of chains built of inter-molecular hydrogen bonds O-H…O.     

Aqueous Equilibrium and Solution Structural Studies of the Interaction of N,N′-bis(4-imidazolymethyl)etylenediamine with Ca(II), Cd(II), Co(II), Cu(II), Mg(II), Mn(II), Ni(II), Pb(II) and Zn(II) Metal Ions

Divalent metal complexes of N,N′-bis(4-imidazolymethyl)etylenediamine (EMI) have been studied using potentiometric and spectroscopic techniques (UV-Vis and NMR methods) in aqueous 0.1 mol⋅L⁻¹ KCl supporting electrolyte at 25 °C. Final models and overall stability constants for the complexes of Ca(II), Cd(II), Co(II), Cu(II), Mg(II), Mn(II), Ni(II), Pb(II) and Zn(II) have been established by potentiometry for all M(II)–EMI systems, except for Co(II)–EMI. The data revealed that EMI forms ML complexes with all M(II)–EMI systems, which is the dominant species over a wide range of pH except for the Ca(II)–EMI and Mg(II)–EMI systems. Formation of the MnHL complex was also found for Mn(II)–EMI solutions. In addition, the UV-Vis and ¹H NMR results allowed us establish the coordination modes for the metal complexes between EMI with Cd(II), Cu(II), Ni(II) and Zn(II).     

Interaction of Co(II), Ni(II), Cu(II), and Zn(II) with N,N′-(aldose)2-thiocarbohydrazide: synthesis,electrochemistry, and spectral characterization

Complexes of Co(II), Ni(II), Cu(II), and Zn(II) with N,N′-(aldose)₂–thiocarbohydrazide (LH₂) were synthesized, isolated as solid products and characterized by analytical means as well as by spectral techniques, FTIR, ¹H NMR, EPR, UV spectroscopy, and CD. All the metal ions formed M[LH]X complexes. Molar conductance values in DMF indicate non-electrolytic complexes. In DMSO with tetramethylammonium chloride supporting electrolyte, the copper complex displays irreversible cyclic voltammetric responses with E _p near ?0.621 and 0.461 V versus Ag/AgCl at scan rate of 0.1 V s^?1. Probable structures for the complexes are proposed.     

Mixed-ligand complexes of iron(II), iron(III), copper(II), and cobalt(II) with pyrazolonic and 2,2′-bipyridine ligands

New mixed-ligand complexes, [M₂(BAMP)(bipy)₂][MCl₄]₂, M=Co⁺²(1), Cu⁺²(2), [M₂(TAMEN)(bipy)₂][MCl₄]₂, M=Fe⁺²(3), Co²⁺(4), and [Fe₂(TAMEN)(bipy)₂][FeCl₆]₂ (5), where BAMP and TAMEN stand for the Mannich bases N,N′-bis(antipyryl-4-methylene)-piperazine and N,N′-tetra(antipyryl-4-methylene)-1,2-ethane-diamine, respectively, have been obtained and characterized by elemental analyses, conductometric and magnetic susceptibility measurements at room temperature, mass spectrometry, UV-Vis, infrared, and mass spectroscopy, and ¹H NMR spectra for the ligands.     

Thermal behaviors of N-pyrrolidine-N′-(2-chlorobenzoyl)thiourea and its Ni(II), Cu(II), and Co(III) complexes

The N-pyrrolidine-N??-(2-chlorobenzoyl)thiourea, HL, and their Ni(II), Cu(II), and Co(III) complexes (NiL₂, CuL₂, and CoL₃) have been synthesized and characterized. The thermal decomposition reactions of all the compounds have been investigated by DTA/TG combined systems. The mass spectroscopy technique has been used to identify the products during pyrolytic decomposition. The pyrolytic final products have been analyzed by X-ray powder diffraction method. After comparison of thermogravimetric and mass results of HL, NiL₂, CuL₂, and CoL₃, the decomposition mechanism of these compounds have been suggested. The thermal stability of the Ni(II) and Cu(II) complexes according to the thermogravimetric curves follows the sequence: NiL₂?<?CuL₂. The values of the activation energy, E _a, have been obtained using model-free (Kissenger?CAkahira?CSunose, KAS, Flyn?CWall?COzawa, FWO, and Isoconversional) methods for all decomposition stages. The E _a versus the extent of conversion, ??, plots show that the values of E _a varies as ??. Thirteen kinetic model equations have been tested for selecting correct reaction models. The optimized value of E _a and Arrhenius factor, A, have been obtained using the best model equation. The thermodynamic functions (??H*, ??S*, and ??G*) have been calculated using these values.     

Syntheses and structural characterizations of a new benzyl(4-methoxyphenyl)dithiophosphinic acid and its Ni(II), Co(II), Zn(II), Cd(II), and Ni–pyridine complexes

Benzyl(4-methoxyphenyl)dithiophosphinic acid (HL) was obtained as solid and was treated with the NiCl₂6H₂O, CoCl₂6H₂O, ZnCl_2, and CdCl₂ to prepare its Ni(II), Co(II), Zn(II), and Cd(II) complexes. The nickel complex was further treated with pyridine which led to the formation of octahedral dipyridine derivative. HL was obtained through the addition reaction of the perthiophosphonic acid anhydride Lawesson reagent, (LR), [2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide], with the corresponding Grignard compound (benzylmagnesium bromide) in diethyl ether medium.

The complexes were all of the stoichiometry of [M(L)₂]_x, with x = 1 for M = Ni²⁺ and x = 2 for M = Co²⁺, Cd²⁺ and Zn²⁺. The coordination geometry was square planar in the nickel(II) complex and tetrahedral in the others. Similar to many other nickel(II) complexes, the Ni(L)₂ reacts reversibly with pyridine to yield the octahedral complex ({(Py)₂Ni(L)₂}).

The compounds were characterized by elemental analysis; MS, FTIR, and Raman spectroscopies. The magnetic susceptibilities of the complexes were measured to confirm the hybridization patterns and the geometries. Single-crystal X-ray analyses of Ni(L)₂ and [Co(L)₂]₂ complexes were also carried out to prove the molecular topologies.     

Complex formation of Cu(II), Ni(II), Zn(II), Co(II), and Cd(II) acetates with 3,3′,4,4′,5,5′-hexamethyldipyrrolylmethene

The reactions of complex formation of Cu(II), Co(II), Zn(II), Ni(II), and Cd(II) acetates with 3,3′,4,4′5,5′-hexamethyl-2,2′-dipyrrolylmethene (HL) in DMF were studied by the electronic spectroscopy and calorimetric titration methods at 298.15 K. The main products of the above reactions are [ML₂] chelates. In the case of Cu and Ni salts, the process occurs through the spectrally recorded stage of formation of the heteroligand [ML(AcO)] complexes. The reaction with Cd acetate terminates at the stage of the heteroligand complex formation due to the large radius and decreasing electron affinity of the Cd²⁺ ion. The effect of the metal nature appears in the increasing thermodynamic stability of single-type complexes in the series [ML₂]: Ni(II) < Zn(II) < Co(II) < Cu(II) and [ML(AcO)]: Cd(II) < Ni(II) < Cu(II).     

Microwave assisted synthesis and characterization of N,N′-bis(salicylaldehydo)ethylenediimine complexes of Mn(II), Co(II), Ni(II), and Zn(II)

Microwave chemistry is a green chemical method that improves reaction conditions and product yields while reducing solvent amounts and reaction times. The main aim of this article is to synthesize the tetradentate N₂O₂ ligand [HO(Ar)CH=N–(CH₂)₂–N=CH(Ar)OH] and manganese(II), cobalt(II), nickel(II), and zinc(II) complexes of the type ML by classical and microwave techniques. The resulting Schiff base and its complexes are characterized by ¹H NMR, infrared, elemental analysis, and electronic spectral data. The ligand and its Co(II) and Mn(II) complexes were further identified by X-ray diffraction and mass spectra to confirm the structure. The results suggest that the metal is bonded to the ligand through the phenolic oxygen and the imino nitrogen.