Manganese(II), nickel(II) and copper(II) complexes of (1,3-bis-aminomethyl) cyclohexane-N,N,N′,N′-tetrakisbenzimidazole

Summary Mn^II, Ni^II and Cu^II complexes of (1,3-bis-aminomethyl)-cyclohexane-N,N,N,N-tetrakisbenzimidazole (CDTB) have been prepared and characterized by spectral techniques. The complexes are monomeric and pseudo-octa-hedral, as evidenced by their e.p.r. spectra and analytical data. Parameters ², ², ² and for Cu^II complexes, and the crystal field splitting parameter (10 Dq) together with the Nephelauxetic ratio (), for Ni^II complexes, are reported.     

Synthesis and X-ray crystal structures of N,N,N′,N′-tetraalkylpyridine-2,6-dithiocarboxamides (S-dapt) complexes of cobalt(II) and nickel(II)

Reactions of anhydrous CoX₂ (X?=?Br^?, SCN^?) and Ni(ClO₄)₂ with N,N,N′,N′-tetraisobutylpyridine-2,6-dithiocarboxamides (S-dbpt), N,N,N′,N′-tetraisopropyl pyridine-2,6-dithiocarboxamides (S-dppt), and N,N,N′,N′-tetraethylpyridine-2,6-dithiocarboxamides (S-dept) lead to the formation of [Co(S-dbpt)Br₂] (1), [Co(S-dppt)(SCN)₂] (2), and [Ni(S-dept)₂]·(ClO₄)₂·H₂O (3), respectively. The X-ray crystal structures of the three S-dapt ligands and three complexes along with spectroscopic analyzes are presented. The molecular structure investigations of the S-dapt ligands show that the thiamide planes are twisted with respect to the pyridine ring, which is more in the case of phenyl groups. The structures of the Co(II) complexes reveal that an increase in steric crowding on the amide side arms of the ligands has no substantial effect on the geometry adopted by the corresponding complexes. The Co(II) gives only 1?:?1 five-coordinate, ion-paired complexes with a distorted square pyramidal geometry. Ni(II), on the other hand, prefers an octahedral geometry with 1?:?2 metal–ligand ratio. The coordination behavior of S-dapt has been compared to the analogous oxo(O-daap) ligands. Lesser propensity of S atom to get involved in H-bonding interactions ensures an S-N-S type of tridentate coordination by S-dapt.     

Extraction and complexation of copper(II) with para-tert-butylbenzhydrazide and its N′,N′-dimethyl derivative

The extraction of copper(II) with the para-tert-butylbenzoic acid hydrazide and related N??,N??-dimethyl derivative was studied. The composition and structure of the extracted complexes were determined, the mechanism of extraction of copper(II) in different media was suggested, the extraction constant was calculated. The copper(II) complex compounds with these reagents were isolated.     

Syntheses and structures of cobalt(II), nickel(II), and copper(II) complexes with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides (O-daap) containing nitrate as the counter ion

Reactions of M(NO₃)₂?·?xH₂O [M?=?Co(II), Ni(II), and Cu(II)] with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides(O-daap) in CH₃CN yield [Co(O-dmap)(NO₃)₂] (1), [Co(O-deap)(NO₃)₂] (2), [Co(O-dpap)(NO₃)₂] (3), [Ni(O-dmap)(H₂O)₃](NO₃)₂] (4), [Ni(O-deap)(H₂O)₂(NO₃)](NO₃)] (5), [Cu(O-deap)(NO₃)₂] (6), and [Cu(O-dpap)(NO₃)₂] (7). X-ray crystal structures of 1, 2, 4, 5, and 7 reveal that O-daap ligands coordinate tridentate to each metal, O–N–O, with nitrate playing a vital role in molecular and crystal structures of all the complexes. The coordination geometry in the two Co(II) complexes, 1 and 2, is approximately pentagonal bipyramidal with nitrate bonded in a slightly unsymmetrical bidentate chelating mode. [Ni(dmap)(H₂O)₃](NO₃)₂ (4) and [Ni(deap)(H₂O)₂(NO₃)](NO₃) (5) exhibit octahedral geometry, the former containing uncoordinated nitrate while the latter has one nitrate coordinated unidentate and the other nitrate outside the coordination sphere. The Cu(II) in [Cu(dpap)(NO₃)₂] (7) occupies a distorted square pyramidal geometry and is linked to two unidentate nitrates, although one nitrate is also involved in a weak interaction with the metal through its other oxygen. IR spectra and other physical studies are consistent with their crystal structural data. O-dmap?=?N,N,N′,N′-tetramethylpyridine-2,6-dicarboxamides; O-deap?=?N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamides; and O-dpap?=?N,N,N′,N′-tetraisopropylpyridine-2,6-dicarboxamides.     

Extraction of copper(II) with N-(para-tert-butylbenzoyl)-N′,N′-dialkylhydrazines

Extraction of Cu(II), Co(II), Ni(II), and Zn(II) with N-(para-tert-butylbenzoyl)-N??,N??-dialkylhydrazines was studied. In contrast to other listed elements, copper(II) is extracted with these reagents in a wide pH range and NH₃ concentrations, which provides its selective separation. Effect of chain length of the N??,N??-alkyl groups and solvent nature on copper extraction and its stripping conditions were determined. Extraction constants were calculated. Ammonium salts decrease the extraction degree of copper(II). The studied reagents are superior to the known industrial reagent of ??-diketone class, LIX 54, in terms of copper(II) extraction efficiency from ammonia media.     

Synthesis,characterization and nucleolytic property of bis(N,N′-dimethylglycinato)copper(II)

Aquabis(N,N-dimethylglycinato)copper(II) dihydrate, [Cu(dmg)₂(H₂O)]·2H₂O, has been synthesized and characterized by elemental analysis, FT-IR, magnetic data, thermal analysis, solution UV-visible spectroscopy, X-ray crystal structure analysis and electrospray ionization mass spectroscopy. The square pyramidal copper(II) complex crystallizes in the orthorhombic space group P2₁2₁2₁. The complex cleaves circular plasmid DNA (pBR322) in the presence of H₂O₂. The extent of cleavage varies with the concentration range of the complex, the type of buffer used, pH of buffer and the concentration of H₂O₂. Hydroxyl radical scavenger can inhibit the nucleolytic ability of this complex.     

Complexation of copper(II) with 2′,2′-dialkyl-para-tert-butylbenzohydrazides

The complexation of copper(II) with 2′,2′-dimethyl-, 2′,2′-dibutyl-, and 2′,2′-diisobutyl-para-tert-butylbenzohydrazide in water-ethanol media was studied. The reagents (HL) formed [Cu(HL)]²⁺ and [Cu(HL)₂]²⁺ cationic complexes in a weakly acidic medium and uncharged CuL₂ complexes in an alkaline medium. logK _st was calculated for these complexes. The effect of 2′,2′-alkyl radicals on the stability of the complexes was considered. The obtained results were compared with data on the complexation of copper(II) ions with 2′,2′-dialkylbenzohydrazides.     

Mixed valence copper(I)–copper(II) complexes of N,S donor ligands and their 7,7′,8,8′-tetracyanoquinodimethane derivatives

The reaction of the CuCl2·2H2O with the N,S donor ligands bis(o-aminobenzenethio)ethane, bis(o-aminoben-zenethio)propane and bis(o-aminobenzenethio)butane (abbreviated as eN2S2, pN2S2 and bN2S2, respectively) yielded mononuclear CuII complexes of stoichiometry Cu(L)Cl2 (L=eN2S2, pN2S2 or bN2S2). When the reactions were performed in the presence of 2,6–diacetylpyridine and NaClO4, binuclear mixed valence CuI–CuII complexes of stoichiometry [Cu2(L)][ClO4]3 (L=eN6S4, pN6S4 or bN6S4) were formed. Metatheses between the binuclear complexes and the lithium salt of 7,7,8,8-tetracyanoquinodimethane (TCNQ) yielded complexes of stoichiometry Cu2(L)(TCNQ)2 (L=eN6S4, pN6S4 or bN6S4). All of the complexes were characterised by analytical and spectroscopic techniques.     

Crystal structure of copper(II) chelate with para-(tert-butyl)benzoic acid N′,N′-dimethylhydrazide

X-Ray diffraction analysis was performed for the copper(II) chelate with para-(tert-butyl)benzoic acid N??,N??-dimethylhydrazide, Cu(p-(tert-Bu)C₆H₄CONHNMe₂)₂ (I). The reagent functions as a bidentate (O,N(2)) ligand giving a five-membered copper-containing ring. The molecule is centrosymmetric. The Cu atom and the metal rings lie in the same plane. The coordination polyhedron of copper is a slightly distorted square. The crystals are monoclinic: a = 16.2634(14) ?, b = 9.0415(8) ?, c = 9.6415(9) ?, ?? = 90°, ?? = 100.052(7)°, Z = 2, space group P2₁/c.     

Synthesis and structural features of copper(II) complexes of N,N,N′,N′-tetramethylethylenediamine with 2-chlorobenzoate1− and 2-hydroxybenzoate1−

Abstract

Two copper(II) coordination complexes, formulated as [Cu(tmen)(Clba)₂] (1) and [Cu(tmen)(Hsal)₂·H₂O] (2) (where tmen?=?N,N,N′,N′-tetramethyl ethylenediamine (C₆H₁₆N₂), Clba^1? = 2-chlorobenzoate (C₇H₄ClO₂^1?), and Hsal^1? (C₇H₅O₃^1? = monoanion of o-hydroxybenzoic acid (salicylic acid)), have been synthesized and characterized by elemental combustion analysis, spectroscopic techniques, thermal studies, and single crystal X-ray analyses. Complex 1 consists of two distinct monomeric units in which the coordination environment around the central copper(II) ion is a distorted octahedron with a CuN₂O₄ chromophore, constituted by a chelating tmen molecule, and two 2-chlorobenzoate^1? anions coordinated through their carboxylate-O atoms in an asymmetrical bidentate fashion. Complex 2 is also a monomer and consists of an CuN₂O₃ chromophore, in which tmen is coordinated to Cu(II) through its two N atoms in a chelating bidentate fashion, and an aqua-O and the two o-hydroxybenzoate^1? (HSal^1?) anions are coordinated through one of their carboxylate-O atoms in a monodentate mode, forming a square pyramidal structure. Hydrogen bonding interactions especially of O–H…O, N–H…O, and C–H…Cl types interweave monomeric units and stabilize the overall crystal structures in both complexes. Thermal analysis and antibacterial activities of 1 and 2 against various bacterial strains were also investigated.     

Syntheses and X-ray crystal structures of five- and six-coordinate copper(II) complexes of N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides containing–OClO3 and–OSO2CF3 counter ions

Reactions of anhydrous copper(II) chloride with NaX (1 : 1 or 1 : 2) and AgX (1 : 2) containing appropriate N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides(O-daap) in CH₃CN yield monosubstituted five-coordinate [Cu(L₁)Cl(CF₃SO₃)] (1), [Cu(L₂)Cl(ClO₄)] (2), [Cu(L₃)Cl(ClO₄)] (3), and six-coordinate [Cu(L₂)(CF₃SO₃)₂] · H₂O (4) (X = ?OClO₃ and–OSO₂CF₃; L₁ = N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamides; L₂ = N,N,N′,N′-tetraisopropylpyridine-2,6-dicarboxamides; L₃ = N,N,N′,N′-tetraisobutylpyridine-2,6-dicarboxamides). The structures of these complexes have been determined by X-ray crystallography. The Cu²⁺ in 1–3 adopts distorted square-pyramidal geometry, while 4 exhibits octahedral structure. Steric factors in conjunction with lattice effects and the nature of the anions are responsible for the variety in coordination spheres. These compounds undergo extensive intermolecular H-bonding to give to 2-D sheets extending along various planes.     

Thermal decomposition kinetics of polymeric complexes of copper(II) and mercury(II) with N,N′-bis(dithiocarboxy)piperazine

The thermal decomposition behaviour of polymeric complexes of Cu(II) and Hg(II) with N,N-bis(dithiocarboxy)piperazine is investigated in air by thermogravimetric (TG), derivative thermogravimetric (DTG) and differential thermal analysis (DTA) techniques. The kinetic parameters (non-isothermal method) for their decomposition have been evaluated by graphical as well as by least-squares methods. The equations of Coats-Redfern, Freeman-Carroll and Horowitz-Metzger have been applied. The results indicate that the values ofE,A and S obtained by these three different methods agree well. It was also found that the decomposition of these metal chelates follow first-order kinetics.

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Zusammenfassung Mittels TG, DTG und DTA wurde das thermische Zersetzungsverhalten von Polymerkomplexen aus Cu(II) bzw. Hg(II) mit N,N-Bis(dithiocarboxy)piperazin an Luft untersucht. Für ihre Zersetzung (nichtisotherme Methode) wurden die kinetischen Parameter sowohl graphisch als auch durch Methoden mit den kleinsten Fehlerquadraten ermittelt. Dabei wurden die Gleichungen von Coats-Redfern, Freeman-Carroll und von Horowitz-Metzger angewendet. Alle drei Verfahren zeigen übereinstimmende Resultate fürE, A undS. Es wurde weiterhin gefunden, daß diese Metallchelate einer Reaktion erster Ordnung unterliegen.

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The authors are thankful to Prof. C. G. R. Nair, Head of the Department of Chemistry, University of Kerala and Dr. M. P. Kannan, Department of Chemistry, University of Calicut for some helpful discussions.     

Synthesis and magnetic properties of copper(II)-cobalt(II) complexes ofN,N′-1,2-propanedisalicylamidatocuprate(II)

Summary The binuclear metal complexes [Cu(sampn)Co(L)₂] (L=bipy, phen), have been prepared by the reaction of sodiumN,N-1,2-propanedisalicylamidatocuprate(II) heptahydrate, Na₂[Cu(sampn)] 7H₂O, with a divalent metalion, and 2,2-bipyridine or 1, 10-phenathroline. The complexes were characterized by variable-temperature magnetic susceptibility measurements; the results indicate that a weak antiferromagnetic spin-exchange interaction operates between the metal ions.     

Hydrogen-bonded networks based on manganese(II), nickel(II), copper(II) and zinc(II) complexes of N,N′-dimethylurea

A project related to the crystal engineering of hydrogen-bonded coordination complexes has been initiatied and some of our first results are presented here. The compounds [Mn(DMU)₆](ClO₄)₂ (1), [Ni(DMU)₆](ClO₄)₂ (2), [Cu(OClO₃)₂(DMU)₄] (3) and [Zn(DMU)₆](ClO₄)₂ (4) have all been prepared from the reaction of N,N-dimethylurea (DMU) and the appropriate hydrated metal perchlorate salt. Crystal structure determinations of the four compounds demonstrate the existence of [M(DMU)₆]²⁺ cations and ClO₄ ^– counterions in (1), (2) and (4), whereas in (3) monodentate coordination of the perchlorate groups leads to molecules. The [M(DMU)₆]²⁺ cations and ClO₄ ^– anions self-assemble to form a hydrogen-bonded one-dimensional (1D) architecture in (1) and different 2D hydrogen-bonded networks in (2) and (4). The hydrogen bonding functionalities on the molecules of (3) create a 2D structure. The complexes were also characterised by room-temperature effective magnetic moments and i.r. studies. The data are discussed in terms of the nature of bonding and the known structures.     

Interconversion of copper(II) to copper(I): synthesis,characterization of copper(II) and copper(I) 2,2′-biquinoline complexes and their microbiological activity

The complexes [Cu(biq)₂]Cl₂ and [Cu(biq)₂]BF₄·biq (biq?=?2,2′-biquinoline) have been prepared and characterized. The interconversion to copper(I) complex [Cu(biq)₂]BF₄·biq, from [Cu(biq)₂]Cl₂ has been established. The new complexes have been characterized by elemental analysis, conductivity and magnetic measurements, IR, UV-vis and ¹H- and ¹³C-NMR spectroscopy. The X-ray analysis of the complex [Cu(biq)₂]BF₄·biq supports the assumption of the interconversion of copper(II) to copper(I) in this case. The crystal structure shows that geometry around the metal is severely distorted from T_d, and displays many supramolecular motifs incorporating both hydrophobic (aryl···aryl) and hydrophilic (C–H···F) intermolecular interactions. The microbiological activity of the complexes against bacteria and fungi was found to be high against Candida albicans, and slight to moderate against bacteria. The antimicrobial activity of [Cu(biq)₂]BF₄·biq was slightly better than that observed for [Cu(biq)₂]Cl₂ against both bacteria and fungi.     

Cobalt(II) and copper(II) complexes ofN,N′,N″,N‴-tetra(2-cyanoethyl)-1,4,8,11-tetraazacyclotetradecane

Summary Cobalt(II) and copper(II) complexes of the title ligand, TCEC, as well as a cobalt(II) complex ofN,N,N",N'-tetra (1-methyl-2-cyanoethyl)-1,4,8,11-tetraazacyclotetradecane, TMCEC, have been isolated and spectrally characterized.     

Catalase activity of cobalt(II) complexes with N,N,N′,N′-tetrasubstituted thiocarbamoylsulfenamides

On the base of the kinetic and activation parameters of the hydrogen peroxide decomposition in the presence of chelates of CoX₂ salts (X = Cl, Br, I, NCS) with N,N,N′,N′-tetrasubstituted thiocarbamoylsulfenamides containing exocyclic (out-of-chelate) fragments of dimethylamine (I), piperidine (II), and piperazine (III) the nature of acido-ligands influence on catalase activity of complexes I–III was revealed, depending on the structure and composition of the chelating ligand. Mononuclear complexes I(Br) and II(Br) can transform into 10-membered binuclear macrochelate intermediates.     

Thermochemistry of Cu(II) and Ni(II) complexes with N,N-di-n-butyl-N′-thenoylthiourea and N,N-di-iso-butyl-N′-thenoylthiourea

Two substituted N-acylthioureas and the respective Ni(II) and Cu(II) complexes were synthesized, namely: N,N-di-n-butyl-N′-thenoylthiourea (Hnbtu); N,N-di-iso-butyl-N′-thenoylthiourea (Hibtu); bis[N,N-di-n-butyl-N′-thenoylthioureato]nickel(II), [Ni(nbtu)₂]; bis[N,N-di-n-butyl-N′-thenoylthioureato]copper(II), [Cu(nbtu)₂]; bis[N,N-di-iso-butyl-N′-thenoylthioureato]nickel(II), [Ni(ibtu)₂]; bis[N,N-di-iso-butyl-N′-thenoylthioureato]copper(II), [Cu(ibtu)₂]. The standard (p^° = 0.1 MPa) molar enthalpies of formation and sublimation of the two N-acylthioureas were measured, at T = 298.15 K, by rotating-bomb combustion calorimetry and Calvet microcalorimetry, respectively. The standard (p^° = 0.1 MPa) molar enthalpies of formation of the Ni(II) and Cu(II) complexes were determined, at T = 298.15 K, by high precision solution–reaction calorimetry. From the results obtained, the enthalpies of hypothetical metal–ligand and metal–metal exchange reactions, in the gaseous phase, were derived, thus allowing a discussion of the gaseous phase energetic difference between the complexation of Ni(II) and Cu(II) to 1,3-ligand systems with (S,O) ligator atoms.     

Monomeric copper(II) and nickel(II) complexes of N,N,N′,N′-tetrakis [(2-benzimidazolyl)methyl]-1,2-cyclohexanediamine], a chelating ligand containing imidazole groups

Summary Cu^II and Ni^II coordination compounds with N,N,N,N-tetrakis[(2-benzimidazolyl)methyl]-1,2-cyclohexanediamine (CDTB) have been prepared and characterized. The crystal structure of [Cu(CDTB)](ClO₄)₂ has been determined. The geometry around the Cu atom is highly irregular and can best be described as a cis-distorted octahedron, with four short CuN bond distances of 1.988(3) Å and 2.028(3) Å, and two very long CuN bond lengths of 2.543(4) A. The cis NCuN chelate angles in the complex range from 68.8(2) for N(1)CuN(1) to 141.03° for N(4)CuN(1). The cyclic voltammogram of the complex shows a fully reversible one-electron redox wave at E _1/2 = 0.162V versus standard calomel electrode, corresponding to the Cu^I/II redox couple. The structure of [Ni(CDTB)](NO₃)₂ ·EtOH has also been determined. The geometry around the Ni atom in this compound can be described as distorted octahedral, with N(4), N(4), N(1), N(1) as the ligating atoms in the basal plane, with cis chelate angles ranging from 79.37(10) to 120.9(2)° with the trans N(2)NiN(2) angle at 175.1(2)°. The structural differences in these two compounds are undoubtedly electronic rather than steric.     

Synthesis and magnetic properties of heterobinuclear copper(II)–iron(II) complexes with N,N′-bis(2-aminopropyl)oxamidocopper(II)

Six new -oxamido heterobinuclear complexes, namely [Cu(oxap)Fe(L)2]SO4, where oxap denotes the N,N-bis(2-aminopropyl)oxamido dianion and L represents 1,10-phenanthroline (phen); 5-nitro-1,10-phenanthroline (NO2-phen); 5-chloro-1,10-phenanthroline (Cl-phen); 5-methyl-1,10-phenanthroline (Me-phen); 2,2-bipyridine (bpy); and 4,4-dimethyl-2,2-bipyridine (Me2bpy), have been synthesized and characterized by elemental analyses, i.r. spectra, electronic spectra, magnetic moments (at room temperature) and molar conductivity measurements. The temperature dependent magnetic susceptibilities of [Cu(oxap)Fe(bpy)2]SO4 (1) and [Cu(oxap)Fe(phen)2]SO4 (2) have been studied in the 4.2–300K range, giving the exchange integrals J=–20.9cm–1 for (1) and J=–22.5cm–1 for (2). These results are commensurate with antiferromagnetic interactions between adjacent metal ions within each molecule.