Binuclear Copper(II) Complexes in which other copper(II) complexes are coordinated as bidentate ligands

Twelve new copper(II) complexes in which N,N′-bis-(2-pyridylmethyl)-oxamidatocopper(II) or N,N′-bis(2-pyridylethyl)-oxamidatocopper(II) coordinates as a bidentate ligand have been isolated and characterized. These complexes have a structure bridged by the oxamide group (including two tetranuclear complexes formed by olation of two binuclear complexes, of. Fig. 1), and possess Cu? Cu interaction resulting in a sub-normal magnetic moment at room temperature. In one of them, [Cu₂(PMoxd) (bipy)₂] (NO₃)₂ (cf. Fig. 2), each copper(II) ion has a five-coordinated environment.     

Magnetic Properties and Mössbauer Spectra of Binuclear Copper(II) and Tetranuclear Diiron(III)-porphyrin-dicopper(II) Complexes with Schiff-Base Ligands of 2-lmidazolealdehyde and Acetylpyrazine

The binuclear copper(II) and tetranuclear diiron(III)-porphyrin-dicopper(II) complexes with the Schiff-base ligands of N,N′-bis(2-imidazolaldehyde)ethylenediimine, N,N′-bis(2-imidazolaldehyde)-p-phenyldiimine, N,N-bis(acetylpyrazine)-ethylenediimine and N,N′-bis(acetylpyrazine)-p-phenyldiimine have been prepared and characterized. The magnetic data indicated that the spin ground states and the magneic interaction between Cu(II)-Cu(II) or Fe(III)-Cu(II) are dependent on the nature of the bridging ligands. A weak antiferromagnetic interaction between Fe(III) and Cu(II) is evident from the temperature-dependent magnetic measurements. The Mössbauer spectra of iron(III) -porphyrin sites showed an asymmetric quadrupole doublet consistent with high-spin iron(III) S = 5/2.     

A new double asymmetric μ 1,1-azido bridged binuclear copper(II) complex: crystal structure and magnetic properties

A new double asymmetric μ_1,1-azido bridged binuclear copper(II) complex, [Cu₂(μ_1,1-N₃)₂(Him2-py)₂(N₃)₂] (Him2-py?=?2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-hydroxy), has been synthesized and characterized structurally and magnetically. The crystal structure shows this complex is binuclear with copper(II) in a distorted square-pyramidal geometry, bridged by double asymmetric end-on azide ligands. The variable temperature magnetic susceptibility analyses reveal weak antiferromagnetic interaction mediated by the bridge.     

Magnetic interactions in a new heterospin complex involving nitroxide radical and oxamido-bridged copper(II)

A new binuclear copper(II) complex [Cu₂(oxpn)(IM2py)₂](ClO₄)₂, containing four spin carriers with pyridyl-substituted nitroxide radicals has been synthesized and characterized structurally and magnetically (oxpn?=?N,N′-bis(3-aminopropyl)oxamido, IM2py?=?2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl). The structure of the complex consists of centrosymmetric trans oxamido-bridged copper(II) binuclear units and nitroxide radicals. The coordination geometry around each copper atom is distorted square pyramidal and the apical position is occupied by a nitrogen atom of the imidazoline ring of a radical ligand. Magnetic analysis indicates that the complex exhibits strong antiferromagnetic coupling between copper(II) ions through the oxamido bridge and a ferromagnetic interaction between copper(II) ions and radical ligands. The magnetic behaviour is discussed with reference to the crystal structure.     

Mono- and binuclear copper(II) complexes of saccharin with 2-pyridinepropanol synthesis,spectral, thermal and structural characterization

Mono- and binuclear copper(II) saccharinate (sac) complexes containing 2-pyridinepropanol (pypr) have been prepared and characterized by elemental analyses, i.r., u.v.–vis., magnetic measurements and single crystal X-ray diffraction. The copper(II) ion in trans-[Cu(pypr)₂(sac)₂] has –1 site symmetry and is octahedrally coordinated by two bidentate neutral pypr (N, O) and two sac (O) ligands. The binuclear copper(II) complex, [Cu₂(-pypr)₂(sac)₂], is built up around a centre of symmetry and contains two strongly distorted square–planar coordinated copper(II) ions bridged by two alkoxo groups of the deprotonated pypr ligand, which also coordinates to the copper(II) ions through its nitrogen. In contrast to the mononuclear complex, the sac ligands in the binuclear complex is N-coordinated. The binuclear complex exhibits diamagnetic behaviour. The i.r. spectra and thermal decompositions of both complexes are described.     

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     

Molecular Structures and Magnetic Properties of Strongly Antiferromagnetically Coupled Binuclear Copper(II) Complexes [CU2 REP(μ-X)(Y)2]

The molecular structures of binuclear copper(II) complexes [Cu₂REP(μ-OH)(ClO₄)₂] (4) and [Cu₂REP(μ-Cl)Cl₂] (5), in which REP = deprotonated 2,6-bis(1′-(4′-(2″-pyridyl)-2′-thiabutyl))-4-methylphenol, have been characterized by single-crystal X-ray diffraction. The former crystallizes in the triclinic space group Pl? with a = 10.156(3), b = 12.631(3), c = 25.128(10) Å, α = 92.03(3), β = 96.84(3), γ = 108.02(2),° and Z ? 2. Complex 5 crystallizes in the monoclinic space group C2/c with a = 12.166(2), b = 11.825(2), c = 18.240(4) Å, β = 100.97(2)°, and Z =4. All copper ions are pentacoordinated with ligation to a sulfur, a nitrogen, and the bridging phenolato oxygen of the REP ligand, the exogenous bridge, and a counteranion. The coordination geometry of each copper of the binuclear copper sites is square pyramidal in both 4 and 5. Magnetic susceptibility measurements in the temperature range 6–300 K reveal a strong antiferromagnetic spin exchange in 5 (exchange integral 2J = ?460 cm^?1). A diamagnetic behavior is observed for 4 according to a similar cryomagnetic investigation. The diamagnetism of 4 is further confirmed by measurements of magnetic susceptibility through Evan's method at room temperature. Complex 4 has no EPR signal. The powder EPR spectrum of 5 shows the typical triplet state characteristics with Δm = ±1 transitions at g = 2.15 and a weaker Δm = 2 transition at half field with g = 4.24.     

Reaction of copper(II) fluoro- and chloroacetates with triphenylphosphine oxide

Triphenylphosphine oxide adducts of copper(II) dichloro-, trichloro- and trifluoroacetate were prepared. Electronic, IR and EPR spectra as well as magnetic data over the temperature range 81–301 K have been mainly used for the determination of the stereochemistry and electronic structure of the adducts. The spectral and magnetic behaviours of the adducts are similar to that of copper(II) acetate hydrate. Some correlations between the magnetic and spectral data as well as the acidity of the respective acids are discussed. Cu(F₃CCOO)₂Ph₃PO, represent the first example of a stable binuclear copper(II) trifluoroacetate adduct.     

Structures and magnetic properties of two new heterospin complexes involving nitroxide radicals and oxamido-bridged copper(II)

Two new binuclear copper(II) complexes containing four spin carriers with pyridyl-substituted nitroxide radicals have been synthesized and characterized structurally and magnetically. These complexes are formulated as [Cu₂(oxap)(IM4py)₂](ClO₄)₂ (1) and [Cu₂(oxap)(NIT4py)₂](ClO₄)₂ (2), respectively, in which oxap stands for N,N′-bis(2-aminopropyl). IM4py stands for 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl and NIT4py for 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. The structures of the complexes consist of centro-symmetric trans oxamido-bridged copper(II) binuclear units and nitroxide radicals. In 1 and 2 the copper atoms are in a distorted square plane and radicals (IM4py and NIT4py) coordinate to copper via nitrogen atoms from pyridine rings. Magnetic analysis indicates that 1 and 2 exhibit strong metal-metal antiferromagnetic coupling through oxamido-bridged and antiferromagnetic exchange interactions between copper(II) ion and radicals, respectively. The magnetic behaviors are discussed with reference to their crystal structures.     

ESR study on some copper(Ⅱ)complexes of bis(4''''-benzo-15-crown-5)

ESR measurements have been carried out for some copper(Ⅱ) complexes of bis(4'-ben-zo-15-crown-5) at 77 K.The results of ESR spectrometric titration indicated that the binuclear com-plexes were prepared in the present system.The binuclear complexes revealed characteristic ESRg-anisotropies (gZ相似文献   

Complexing ability of poly[5-vinylsalicylidene-2-aminopyridine] towards different metal(II) salts

Mononuclear and binuclear complexes of poly (5-vinylsalicylidene-2-aminopyridine) ^a)were prepared with Copper(II), Cobalt (II), Nickel(II), Cadmium(II), dioxuranium(II) and Palladium(II) salts. The metal (II) acetates and palladium chloride gave mononuclear complexes, while cupric chloride gave a binuclear complex. The polymer complexes have been characterized on the basis of elemental analysis, u.v., i.r. and magnetic susceptibilty. The stereochemistry and the nature of the complexes are markedly dependent upon the mole ratio of the reactants and the anions. In all complexes the homopolymer was chelated to the metal ion via the nitrogen atom of the azomethine group and oxygen atom of the phenolic, group. The low value of the magnetic moment of binuclear copper complexes is due to the antiferromagnetic interaction between two adjacent copper atoms. The ligand field parameters are calculated and related to the electronic environments.     

SYNTHESIS AND CRYSTAL STRUCTURE OF OXAMIDATO-BRIDGED BINUCLEAR COPPER(II) COMPLEXES

Abstract

The compounds [Cu(oxpn)] (1), [(bpy)(H₂O)Cu(μ-cis-oxpn)Cu(H₂O)] · 2NO₃ · 2H₂O (2) and [(Him)(NO₃)Cu(μ-trans-oxpn)Cu(Him)(NO₃)] (3), where oxpn is the dianion of N,N′-bis(3-aminopropyl)oxamide, bpy is bipyridine and Him is imidazole, were prepared and characterized by elemental analysis and IR spectra. Complex (2) was also studied by thermochemical analysis and its structure determined by X-ray crystallography. The structure of complex (2) consists of binuclear copper(II) molecules in which the copper(II) atoms are bridged by an oxamidato group in the cis conformation resulting a copper-copper distance of 5.21 Å. Both copper(II) ions are in square-pyramidal surroundings with almost coplanar basal planes and a water molecule occupying the apical positions. The N atoms of the oxamidato moiety are trigonal. Two lattice water molecules together with the two coordinated ones hydrogen bond with nitrate ions.     

Cobalt(II) and copper(II) complexes of 3-amino-5-methylisoxazole

Summary Cobalt(II) and copper(II) halide, nitrate, thiocyanate and perchlorate complexes of 3-amino-5-methylisoxazole (3-AMI) have been prepared and characterized by means of magnetic, spectroscopic and molar conductivity measurements. In Cu(3-AMI)₂X₂ compounds (X = Cl, Br, N02) the 3-AMI ligand is bridging and bidentate [N (ring), O(bonded)]. In the other derivatives it is monodentate [N(ring) bonded]. All cobalt(II) complexes have an octahedral stereochemistry, if the Co(3-AMI)₂X₂ derivatives (X = Cl, Br), which are tetrahedral, are excluded. Copper(II) complexes have generally a distorted square pyramidal stereochemistry in the solid state and in solution.     

Synthesis and structure of a complex of copper(II) bromide with bis(benzotriazol-1-yl)methane

The preparation technique of a complex of copper(II) bromide with bis(benzotriazol-1-yl)methane (L), (Cu₂L₂Br₄)_n, is developed. The compound is studied by single crystal and powder X-ray diffraction and static magnetic susceptibility techniques. According to single crystal XRD data, the complex has a layered structure determined by bidentate bridging coordination of L with N(3) and N(3′) atoms to copper(II). The elementary unit of {Cu₂(μ-Br)₂Br₂} polymer has a binuclear structure. The coordination polyhedron is a trigonal pyramid, and the coordination core is CuN₂Br₃. The temperature dependence of effective magnetic moment is studied within an interval of 2–300 K. The nature of the μ_eff(T) dependence indicates that antiferromagnetic exchange interactions dominate in exchange clusters of the complex with an even number of paramagnetic centers. Original Russian Text Copyright ? 2007 by E. V. Lider, A. S. Potapov, E. V. Peresypkina, A. I. Smolentsev, V. N. Ikorskii, A. I. Khlebnikov, and L. G. Lavrenova __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No.3, pp.543–547, May–June, 2007.     

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.     

Synthesis,crystal structure and magnetic properties of a new binuclear copper(II)-copper(II) complex of a macrocyclic oxamide

The binuclear metal complex [Cu(μ-exoO₂)cyclamCu(bpy)](ClO₄)₂·H₂O (bpy?=?2,2′-bipyridine and (exoO₂)cyclam?=?1,4,8,11-tetraazacyclotradecanne-2,3-dione) has been synthesized and characterized by single-crystal X-ray analysis and spectroscopic and magnetic measurements. The structure consists of homobinuclear [Cu(μ-exoO₂)cyclamCu(bpy)]²⁺ cations, a weakly coordinated water molecule and perchlorate ions. In each binuclear unit, Cu1, coordinated by four nitrogen atoms of the macrocyclic organic ligand is connected to Cu2 via the exo-cis oxygen atoms of the macrocyclic ligand with Cu···Cu separations of 5.151?Å; Cu2 assumes square-pyramidal geometry. Magnetic properties measured at 2–300?K show antiferromagnetic exchange between adjacent copper(II) ions.     

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.     

Synthesis,characterization, and biological properties of Ni(II), Co(II), and Cu(II) complexes of Schiff bases derived from 4-aminobenzylamine

New Schiff bases, N,N′-bis(salicylidene)-4-aminobenzylamine (H₂L¹), N,N′-bis(3-methoxysalicylidene)-4-aminobenzylamine (H₂L²), and N,N′-bis(4-hydroxysalicylidene)-4-aminobenzylamine (H₂L³), with their nickel(II), cobalt(II), and copper(II) complexes have been synthesized and characterized by elemental analyses, electronic absorption, FT-IR, magnetic susceptibility, and conductance measurements. For the ligands, ¹H and ¹³C NMR and mass spectra were obtained. The tetradentate ligands coordinate to the metal ions through the phenolic oxygen and azomethine nitrogens. The keto-enol tautomeric forms of the Schiff bases H₂L¹, H₂L², and H₂L³ have been investigated in polar and apolar solvents. All compounds were non-electrolytes in DMSO (～10^?3 M) according to the conductance measurements. Antimicrobial activities of the Schiff bases and their complexes have been tested against Acinobacter baumannii, Pseudomonas aeruginosa, Micrococcus luteus, Bacillus megaterium, Corynebacterium xerosis, Staphylococcus aureus, Escherichia coli, Candida albicans, Rhodotorula rubra, and Kluyveromyces marxianus by the disc diffusion method; biological activity increases on complexation.     

Binuclear metal(II) complexes of a 30-membered hexa-aza macro-cyclic ligand

Summary Schiff base [2 + 2] condensation of p-phthalaldehyde with the triamine 1,7-diamino-4-azaheptane followed by reduction with NaBH₄ gives a 30-membered hexa-aza macrocyclic ligand. A series of binuclear copper(II), nickel(II) and zinc(II) complexes have been prepared and characterized, ¹H-n.m.r., u.v.-vis. and i.r. measurements are reported with associated magnetic and electrochemical studies.Author to whom all correspondence should be directed.     

Complex of copper(II) with phenoxo and hexamethylphosphoramide ligands and its decomposition

The 2,4,6-trichlorophenoxo–hexamethylphosphoramide(HMPA)–copper(II) complex was isolated by the reaction of copper(II) chloride with 2,4,6-trichlorophenol, sodium methoxide, and HMPA in methanol solvent under an atmosphere of nitrogen. This complex has the composition of Cu·HMPA·2(C₆H₂Cl₃O). The molecular weight determination was consistent with the copper(II) complex of binuclear structure. The infrared, electronic, and ESR spectra and magnetic susceptibility of the copper(II) complex are discussed in relation to its structure. Decomposition of the copper(II) complex in refluxing benzene yielded poly(dichlorophenylene oxide), coupling product of the 2,4,6-trichlorophenoxo ligand of the copper(II) complex. Electron spin resonance (ESR) measurements on the copper(II) complex in the solid state in a degassed sealed tube at 120 ± 5°C indicated that the phenoxy radical was generated during the period of decomposition and the intensity of the ESR spectra based on copper(II) ion decreased with the measurement time. From these ESR spectra, a possible initial step involving one electron transfer of the decomposition of the 2,4,6-trichlorophenoxo–HNPA–copper(II) complex is discussed.