Mono- and Binuclear Copper(II) Metal Chelates with 3,5-Di(tert-butyl)salicylaldehyde Acylhydrazones

Some new mono- and binuclear complexes of copper(II) acetate, nitrate, and perchlorate with acylhydrazones of substituted salicylaldehyde derivatives containing bulky tert-butyl substituents are synthesized. The structure and properties of the complexes isolated are shown to be determined by both the structural features of the ligand systems and by the nature of the acido ligands. The exchange parameters 2J ranging from –108 to –125 cm^–1 are calculated for the binuclear copper(II) metal chelates.     

Electrochemical synthesis,structure, magnetic and tribochemical properties of metallochelates of new azomethine ligands,bis-[2-(<Emphasis Type="Italic">N</Emphasis>-tosylaminobenzylidenealkyl(aryl)]disulfides

On the basis of new ligand systems, bis-azomethines of N-tosylaminobenzaldehyde and alkyl(aryl) diaminodisulfides, mono- and binuclear chelates with 4N- and 2N2S-ligand arrangement were chemically (from metal acetates) or electrochemically (from metals in the zero oxidation state) first synthesized and characterized. Mononuclear chelates have a tetrahedral structure. In binuclear copper complexes the magnetic exchange interaction of the antiferromagnetic type was observed. Bisazomethines of disulfides were used as additives to lubricant oils.     

New Binuclear Cu(II) Complexes with Bis(hetarylhydrazones) of 2,6-Diformyl-4-Methylphenol

A series of new binuclear complexes of copper(II) acetate and chloride with bis(hydrazones) based on heterocyclic hydrazines were synthesized. Magnetochemical analysis showed that the resulting metal chelates with different bridging atoms in the exchanged fragment significantly differ in exchange parameters. This fact was explained in terms of geometrical structures of complexes of both types.     

Novel mono-and binuclear complexes of Cu(II) with hydrazones of salicylaldehyde derivatives

A series of new mono-and binuclear metal chelates of Cu(II) with ligands, which are the products of condensation of 3,5-di(tert-butyl)salicylaldehyde with hetarylhydrazines or 4-phenylsemi(thiosemi)carbazide, were synthesized. Their compositions and structures were determined by the elemental analysis, IR and ¹H NMR spectroscopies, magnetochemistry, and conductometry measurements. It was shown for the first time that in the case of hetarylhydrazones, only mononuclear complexes were formed due to steric effect of tert-butyl fragments, whereas arylhydrazones gave binuclear complexes with two Cu atoms bonded by the spin-spin interaction. The exchange parameters 2J were calculated for binuclear metal chelates.     

Synthesis and Physicochemical Study of Binuclear Copper(II) Chelates Containing an Asymmetric Exchanged Fragment

Series of novel binuclear copper(II) chelate complexes containing an asymmetric exchanged fragment were synthesized for the first time. The ligands were the products of condensation of salicylaldehyde derivatives and 1,3-diaminopropan-2-ol or carbonohydrazide. The compositions and structures of the complexes obtained were proved by elemental analysis, IR and ¹H NMR spectroscopy, and magnetochemistry. The antiferromagnetic exchange parameters 2J were determined in terms of the isotropic-exchange HDVV model. The structural effects of exchange channels on these parameters are discussed.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 376–379.Original Russian Text Copyright © 2005 by Lukov, Kogan, Novotortsev, Tupolova, Gevorkyan.     

Synthesis and magnetic properties of new binuclear Cu(II) complexes with tridentate azomethine ligands

New binuclear copper complexes of tridentate azomethine ligands with various combinations of N, O, and S donor centers were prepared by various procedures, including template synthesis. The magnetochemical data obtained for the range 2-300 K suggest the occurrence of antiferromagnetic coupling in most of these chelates. The only exception is the complex containing N-tosyl and N-ethyl donor fragments, in which the ferromagnetic exchange is observed.     

X-ray diffraction, magnetochemical, and quantum chemical study of the structure and properties of binuclear copper(II) complexes

The binuclear chelates of copper(II) based on the tridentate azomethine ligands were synthesized and characterized by elemental analysis, IR, ¹H NMR spectroscopy, X-ray absorption spectroscopy (XANES and EXAFS), and magnetic measurements. The quantum-chemical study of the structure and calculation of magnetic properties of the obtained metal-chelates was performed using the density functional theory with the broken symmetry technique. The performed magnetochemical studies in the temperature range 2?C300 K suggest the existence of antiferromagnetic exchange interaction in all obtained complexes. The parameters of the exchange interaction ?2J > 260 cm^?1 were determined experimentally for all compounds, the experimental data is in a good agreement with the results of quantum-chemical calculations.     

The novel azomethine ligands for binuclear copper(II) complexes with ferro- and antiferromagnetic properties

A series of novel binuclear ferro- and antiferromagnetic Cu(2+) chelates of structurally broadly varied Schiff bases (derived from o-tosylamino(hydroxyl)benzaldehydes and monoalkylated o-phenylenediamine, o-aminophenol, o-aminothiophenol, 1,2-diaminobenzimidazole, 1-aminobenzimidazoline-2-thione) and β-diketimines (derived from 2,6-di-i-Pr-aniline) has been prepared. The tautomerism of the ligands and structureof their copper complexes have been studied with the use of IR, ¹H NMR EPR and EXAFS spectroscopy. Molecular and crystal structure of a β-diketimine copper dimer has been determined by X-ray crystallography. The magnetic measurements (2–300?K) performed for all the complexes showed that the ferro- and antiferromagnetic character of the exchange interaction depends both on the structure of the coordination site (origin of the ligating centers) and the structure of the ligands (in particular, on the type of the cycle annelated to the bridging fragment). Whereas S-binding metal chelates 13 (X?=?NTs, Y?=?S, R?=?H) are diamagnetic, the complexes 15 with annelated azole moieties are ferromagnetic.     

Dilatometric investigation of thermotropic linear chain copper (II) alkanoates

The molar volumes of three binuclear copper (II) alkanoates (cupric octadecanoate, docosanoate, and tetracosanoate) were measured over the temperature range 30°–200 °C, which encompasses their phase transition to a columnar mesophase. A sharp volume increase in a narrow temperature interval about the transition was observed, consistent with a first-order phase transition. Values obtained for the partial molar volume of a methylene group in the columnar mesophase (16.9±0.3 cm³/mol) are between those for crystalline paraffins and for other smectic or discotic mesogens, respectively, indicating a disordered state, but not a complete fusion, of the aliphatic chains of the copper soaps in their columnar mesophase. The stacking period of the binuclear copper complexes in a column was derived from a combination of dilatometric and X-ray data. Its value, 4.64±0.08 Å, is independent of the chain length of the complex and of the temperature.     

Effects of Electronic and Steric Factors on the Magnetic Properties of Novel Homo- and Heterobinuclear Transition-Metal Complexes with Asymmetric 2,6-Diformyl-4-R-Phenol Bis(Hydrazones)

A series of novel homo- and heterobinuclear copper(II), manganese(II), and VO²⁺ complexes with asymmetric 2,6-diformyl-4-R-phenol bis(hydrazones) are synthesized. The values of exchange parameters of these compounds are determined. The comparison of experimental results with the quantum-chemical calculations of the model fragments of binuclear metal chelates allows one to elucidate the main electronic and geometric factors determining the character of changes in the magnetic properties in systematic series of transition-metal complexes with bis(hydrazones).     

Identification of Cu(II)/Cu(III) couples in binuclear copper(II) complexes

A new series of binuclear copper(II) complexes were synthesised and studied by magnetic, spectral, ESR and cyclic voltammetry methods. The μ_eff values per copper atom correspond to the values observed for mononuclear copper(II) complexes. ESR spectral data in solution indicate weak interactions resulting from the electron delocalisation through the ligand system. Two nearly reversible red-ox couples are identified at $\text{+}\text{?}$0.50 V and $\text{+}\text{?}$0.75 V vs SCE. They correspond to Cu(II)αCu(III) red-ox processes, successively occurring at the two copper sites in the binuclear complexes.     

Crystal structure and strong antiferromagnetic interaction of a terephthalate-bridged binuclear copper(II) Complex, [{Cu(dipn)}2(μ-TPHA)](ClO4)2 (dipn = N-(3-aminopropyl)-1,3-propanediamine)

Three binuclear copper(II) complexes bridged by three different bridging ligands: μ-TPHA (terephthalato), μ-PHTA (phthalato) and μ-TCB (tetracarboxylatobenzene) have been synthesized. The crystal structure of [{Cu(dipn)}₂(μ-TPHA)](ClO₄)₂ where dipn = N-(3-aminopropyl)-1,3-propanediamine was solved at room temperature. The [{Cudipn}₂(μ-TPHA)](ClO₄)₂ complex consists of a μ-terephthalato bridging binuclear copper(II) cationic unit and two non-coordinated perchlorate anions. The TPHA ligand bridges in a bismonodentate fashion. The environment of the copper(II) ion is a distorted plane-square-planar coordination sphere. The magnetic properties of the three complexes have been investigated in the 75–300 K range, and show that the geometry of the Cu^II atom is the important factor for magnetic interactions in the terephthalato bridging binuclear copper(II) complexes. This revised version was published online in June 2006 with corrections to the Cover Date.     

Complex Formation of 1,5-Bis(amidomethylsulfonyl)pentane with Copper(II) and Iron(III)

The state of the new antitubercular agent 1,5-bis(amidomethylsulfonyl)pentane in aqueous micellar solution of the nonionic surfactant Bridge 35 and its complexing properties toward copper(II) and iron(III) ions have been studied by spectrophotometry, pH potentiometry (25°C, variable ionic strength), and mathematical modeling. In the concentration range from 5.00 × 10^–5 to 1.00 × 10^–3 M in the presence of Bridge 35, the title compound exists in a neutral monomeric form. It forms 1: 2 mononuclear and 2: 2 binuclear complexes with copper(II) and 1: 1 and 1: 2 mononuclear and 2: 1 binuclear complexes with iron(III). The most favorable structures of 1,5-bis(amidomethylsulfonyl)pentane and its complexes have been simulated in terms of the density functional theory.     

Preparation,characterization and biological evaluation of copper(II) and zinc(II) complexes with Schiff bases derived from amoxicillin and cephalexin

Copper(II) and zinc(II) complexes of Schiff bases obtained by condensation of amoxicillin and cephalexin with salicylaldehyde/pyridoxal were prepared and characterized by microanalytical, thermogravimetric, magnetic and spectroscopic data. All the complexes were found to be six‐coordinate and containing two water molecules. The electron paramagnetic resonance spectral lines exhibited rhombic distortion from axial symmetry, with g_|| > g_? > g_e, in the copper(II) complexes. The geometry of the zinc(II) complexes appears to be octahedral. All the compounds under investigation showed antibacterial activity. The antibacterial activity showed the following trend: copper(II) complexes > zinc(II) complexes > Schiff base ligands > parent drugs. The copper(II) complexes with the Schiff bases derived from cephalexin showed substantially enhanced activity against Pseudomonas aeruginosa compared with the parent drug. All the copper complexes were also found to be active against kaolin paw oedema, whereas the parent drugs were inactive. Copyright © 2005 John Wiley & Sons, Ltd.     

Formation of mono- and binuclear chelates of alkyl-substituted biladiene-a,c with d-metal acetates in pyridine

The complex formation reactions of several d-metal acetates with decamethyl-substituted biladiene-a,c (H₂L) in pyridine (Py) have been studied by electronic spectroscopy. The coordination of H₂L by zinc(II) and copper(II) affords mononuclear complexes [ML], and the coordination by cadmium(II) and mercury(II) produces binuclear heteroligand complexes [M₂L(AcO)₂], whereas the coordination by cobalt(II) gives binuclear biligand complexes [M₂L₂]. In a Py solution in the presence of a copper acetate excess, the ligand in the [CuL] complex is oxidized at the methylene spacer. The thermodynamic formation constants of the mono- and binuclear chelates have been determined from spectral data. The peculiarities of complex formation in pyridine and in dimethylformamide (DMF) are analyzed in comparison.     

Physicochemical Study of New Mono- and Binuclear Copper(II) Complexes with Sterically Hindered Acylhydrazones and Azomethines

Series of new binuclear copper(II) complexes with acylhydrazones and azomethines of substituted derivatives of salicylaldehyde containing bulky tert-butyl substituents were synthesized. The target dimerization of the monomeric fragments of the complexes caused by the steric factors was shown to predetermine the specific features of their magnetochemical behavior. The calculated exchange parameters for the complexes based on acylhydrazones range from –110 to –138 cm^–1 and those for the complexes based on azomethines lie in the interval from –400 to –500 cm^–1.     

Synthesis of copper(II) and nickel(II) triazacycloalkane complexes

Summary Copper(II) and nickel(II) complexes of triazacycloalkanes (pqr-cy), with p, q, r = 2–6, have been prepared and characterized by means of electronic and i.r. spectroscopy, and by magnetic measurements. With nickel(II) mononuclear octahedral complexes [Ni(pgr-cy)₂](CI0₄)₂ are formed, but for copper(II) mononuclear octahedral complexes were obtained only for 222-cy and 223-cy. The other ligands gave copper(II) complexes of the type [Cu(pgr-cy)CI]CIO₄, [Cu(pgr-cy)OH]ClO₄, Or [Cu(pgr-cy)CI_1/2OH_1/2]ClO₄. The hydroxy complexes have low magnetic moments and binuclear hydroxy bridged structures are proposed.Ligand names: e.g. p = q = r = 2 is 1,4,7-triazacvclononane     

Binuclear copper(II) complexes of 5-nitrosalicylaldehyde N(3)-substituted thiosemicarbazones

Summary Binuclear copper(II) complexes with six 5-nitrosalicylaldehyde N(3)-substituted thiosemicarbazones have been prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as i.r., electronic, and ¹H-and ¹³C-n.m.r. spectra of the thiosemicarbazones, have been obtained. The crystal structure of a monomeric copper(II) complex of 5-nitrosalicylaldehyde piperidyl-thiosemicarbazone, H₂5NO₂Sapip, grown from DMF solution, has been solved. Neither the thiosemicarbazones or their binuclear copper(II) complexes show growth inhibitory activity against Aspergillus niger, but the copper(II) complexes show some activity against the fungus Paecilomyces variotii.     

Binuclear and polynuclear complexes of Schiff bases

The data on the synthesis of binuclear and polynuclear homo- and heterometallic complexes of aromatic and heterocyclic (azole) Schiff bases are summarized and systematized. Influence is revealed of the structure (nature of aldehyde and amine moieties and intermetallic bridges) of azomethine binuclear copper chelates on their magnetic characteristics. The complexes with N,N-or S,S-bridging atoms are shown to lead, in general, to ferromagnetic exchange whereas O,O-intermetal binding leads to antiferromagnetic spin-spin coupling.     

Derivatives of the N-(pyrid-2-yl)amides of 3-aminocrotonic acid as chelating ligands

New chelating ligands, N-(pyrid-2-yl)amides of 4,4,4-trichloro-3-amino-2-cyanocrotonic acid have been synthesized from N-(pyrid-2-yl)amides of cyanoacetic acid and CCl₃CN. It has been demonstrated that by the action of butylthiodibutylborane they form binuclear boron chelate complexes. Analogous chelates have also been obtained from the N-(pyrid-2-yl)amides of acetoacetic and 4,4,4-trichloro-3-aminocrotonic acids.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 974–979, April, 1992.