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1.
R. N. Patel Nripendra Singh R. P. Shrivastava K. K. Shukla P. K. Singh 《Journal of Chemical Sciences》2002,114(2):115-124
Equilibrium and solution structural study of mixed-metal-mixed-ligand complexes of Cu(II), Ni(II) and Zn(II) with L-cysteine,
L-threonine and imidazole are conducted in aqueous solution by potentiometry and spectrophotometry. Stability constants of
the binary, ternary and quaternary complexes are determined at 25 ±1°C and in I= 0.1 M NaClO4. The results of these two methods are made selfconsistent, then rationalized assuming an equilibrium model including the
species H3A, H2A, A, BH, B, M(OH), M(OH)2, M(A), MA(OH), M(B), M(A)(B), M2(A)2(B), M2(A)2(B-H), M1M2(A)2(B) and M1M2(A)2(B-H) (where the charges of the species have been ignored for the sake of simplicity) (A = L-cysteine, L-threonine, salicylglycine,
salicylvaline and BH = imidazole). Evidence of the deprotonation of BH ligand is available at alkalinepH. N1H deprotonation of the bidentate coordinated imidazole ligand in the binuclear species atpH > 70 is evident from spectral measurements. Stability constants of binary M(A), M(B) and ternary M(A)(B) complexes follow
the Irving-Williams order. 相似文献
2.
Patel RN Singh N Shukla KK Gundla VL Chauhan UK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(11-12):2603-2610
X-band electron spin resonance (ESR) and UV-vis spectra of a homobinuclear [(Bipy)2Cu-E-Im-Cu(Bipy)2](BF4)3 and a heterobinuclear [(Bipy)2Cu-E-Im-Zn(Bipy)2](BF4)3 complexes, E-Im=2-ethylimidazolate ion have been described as possible models for superoxide dismutase (SOD). Magnetic moment and ESR spectral measurements of the homobinuclear complex have shown an antiferromagnetic exchange interaction. From pH-dependent ESR and UV-vis spectral measurements studies, these complexes have been found to be stable over 8.5-10.5 pH range. These complexes catalyze the dismutation of superoxide (O2-) at biological pH. All the observations indicate that these complexes act as good possible models for superoxide dismutase. 相似文献
3.
A new series of binuclear unsymmetrical compartmental oxime complexes (1–5) [M2L] [M=Cu(II), Ni(II)] have been synthesized using mononuclear complex [ML] (L=1,4-bis[2-hydroxy-3-(formyl)-5-methylbenzyl]piperazine), hydroxylamine hydrochloride and triethylamine. In this system there are two different compartments, one has piperazinyl nitrogens and phenolic oxygens and the other compartment has two oxime nitrogens and phenolic oxygens as coordinating sites. The complexes were characterized by elemental and spectral analysis. Electrochemical studies of the complexes show two step single electron quasi-reversible redox processes at cathodic potential region. For copper complexes E1 pc=−0.18 to −0.62 and E2 pc=−1.18 to −1.25 V, for nickel complexes E1 pc=−0.40 to −0.63 and E2 pc=−1.08 to −1.10 V and reduction potentials are sensitive towards the chemical environment around the copper and nickel atoms. The nickel(II) complexes undergo two electrons oxidation. The first one electron oxidation is observed around +0.75 V and the second around +1.13 V. ESR Spectra of the binuclear copper(II) complexes [Cu2L](ClO4), [Cu2L(Cl)], [Cu2L(NO3)] shows a broad signal at g=2.1 indicating the presence of coupling between the two copper centers. Copper(II) complexes show a magnetic moment value of μeff around 1.59 B.M at 298 K and variable temperature magnetic measurements show a −2J value of 172 cm−1 indicating presence of antiferromagnetic exchange interaction between copper(II) centres. 相似文献
4.
Ghosh D Kundu N Maity G Choi KY Caneschi A Endo A Chaudhury M 《Inorganic chemistry》2004,43(19):6015-6023
Heterobinuclear copper(II)-zinc(II) complexes and their homobinuclear dicopper(II) counterparts (1-4) of two asymmetric ligands (H2L1 and H2L2), based on 2-aminocyclopent-1-ene-1-dithiocarboxylate, are reported. The ligands are capable of providing both donor set and coordination number asymmetry in tandem. Metal centers in these complexes are connected by a micro-alkoxo and a bridging pyrazolate moiety, as confirmed by X-ray structure analyses of 1, 3, and 4. The Cu(1) site in the dicopper complex (1) is square planar and so are the copper sites in the Cu-Zn complexes 3 and 4. The pentacoordinated Zn sites in the latter complexes have distorted TBP geometry (tau = 0.74), while the corresponding Cu site in 1 has a highly distorted square pyramidal structure (tau = 0.54). The Cu...Zn separations in 3 and 4 are 3.3782 and 3.3403 angstroms, respectively, while the Cu...Cu distance in 1 is 3.3687 angstroms. The dicopper complexes are EPR silent at 77 K, in which the copper(II) centers are coupled by strong antiferromagnetic coupling (J = ca. -290 cm(-1)) as confirmed by variable-temperature (4-300 K) magnetic measurements. These compounds (1 and 2) undergo two one-electron reductions and a single step two-electron oxidation at ca. -0.26, -1.40, and 1.0 V vs Ag/AgCl reference, respectively, as indicated by cyclic and differential pulse voltammetry done at subambient temperatures. EPR spectra of 3 and 4 display axial anisotropy at 77 K with the gperpendicular region being split into multiple lines due to N-superhyperfine coupling (AN = 15.3 x 10(-4) cm(-1)). The observed trend in the spin-Hamiltonian parameters, gparallel > gperpendicular > 2.04 and |Aperpendicular| < |Aparallel| approximately (120-150) x 10(-4) cm(-1), indicates a d(x2-y2)-based ground state with tetragonal site symmetry for the Cu(II) center in these molecules. 相似文献
5.
《Journal of Coordination Chemistry》2012,65(2):277-284
Six macrocyclic complexes, were synthesized by reaction of 1,4-bis(2-carboxyaldehyde phenoxy)butane and various amines and their copper(II) perchlorate complexes were synthesized by template effect reaction of 1,4-bis(2-carboxyaldehyde phenoxy)butane, Cu(ClO4)2?·?6H2O and amines. The metal-to-ligand ratios were found to be 1?:?1. Cu(II) metal complexes are 1?:?2 electrolytes as shown by their molar conductivities (ΛM) in DMF (dimethyl formamide) at 10?3?M. The Cu(II) complexes are proposed to be square planar based on elemental analysis, FT–IR, UV–Vis, magnetic susceptibility measurements, molar conductivity measurements, and mass spectra. 相似文献
6.
Marthakutty Joseph V. Suni Maliyeckal R. Prathapachandra Kurup Munirathinam Nethaji Archana Kishore Sarita G. Bhat 《Polyhedron》2004,23(18):3069-3080
Six new copper(II) complexes of 2-benzoylpyridine N(4)-cyclohexyl thiosemicarbazone (HL) have been synthesized and characterized by different physicochemical techniques like molar conductivity measurements, magnetic studies and electronic, infrared and EPR spectral studies. Five of the complexes have been found to possess the stoichiometry [CuLX], where X = Cl (1), Br (2), NO3 (3), NCS (4), N3 (5). The complex prepared from copper sulfate has the composition [Cu2L2SO4] · (H2O)2 (6). In all the complexes the deprotonated ligand, L and the anion were found to be coordinated to the Cu(II) ion. The terdentate nature of the ligand is evident from the IR spectra. The metal ligand bonding parameters evaluated from the EPR spectra indicate strong in-plane σ and in-plane π bonding. The magnetic and spectroscopic data indicate a square planar geometry for complexes 1, 3, 4 and 5, while the complexes 2 and 6 are assigned a square pyramidal geometry. Crystal structure of the complex [CuLCl] reveals two molecules per asymmetric unit of a monoclinic lattice, with space group symmetry P21/n. The complexes [ CuLBr 2] (2) and [CuLNCS] (4) crystallized into triclinic lattices with space group . Compound 2 exists as a thiolate bridged copper(II) dimer. The antimicrobial activity of the ligand and the copper complexes were tested against five types of bacteria isolated from clinical samples. The complexes were found to be active against Bacillus sp., Vibrio cholera O1, Staphylococcus aurus and Salmonella paratyphi. 相似文献
7.
Anupam Singh 《Journal of organometallic chemistry》2005,690(19):4243-4251
Homo-hetero binuclear cationic complexes with the formulation [(η6-arene)RuCl(μ-dpp)(L)]+ (η6-arene = benzene; L = PdCl2 (1a); PtCl2 (1b), and η6-arene = p-cymene; L = PdCl2 (2a); PtCl2 (2b)), [(η6-arene)RuCl(μ-dpp)(L)]2+(η6-arene = p-cymene; L = [(η6-C6H6)RuCl] (2c), and [(η6-C10H14)RuCl] (2d)) were prepared. Molecular structure of the representative homo binuclear complex [{(η6-C10H14)RuCl}(μ-dpp){(η6-C10H14)RuCl}](PF6)2 (2d) was determined crystallographically. Weak interaction studies on the complex 2d revealed stabilisation of the crystal packing by weak inter and intra molecular C-H?X (X = F, Cl, π) and π-π interactions. The C-H?F interactions lead to parallel helical chains and encapsulation of counter anion in self-assembled cavity arising from C-H?π and π-π weak interactions. 相似文献
8.
《Journal of Coordination Chemistry》2012,65(16-18):2510-2525
AbstractTwo triply-bridged dinuclear copper(II) complexes of formula [LCu(μ-OH)(μ-OAc)(μ-X)CuL]X?0.5H2O where L is a bidentate ligand of N-(pyridine-2-ylmethyl)propane-2-amine and X=Cl, 1 and Br, 2 were synthesized and characterized by elemental analyses, spectroscopic techniques (IR, UV–Vis, EPR), thermal analysis, conductance measurements, and single-crystal X-ray structure determination. The structures of both complexes are similar. The complexes show a distorted square-pyramidal arrangement around each copper(II) ion with a CuN2O2X chromophore in which both copper(II) ions are connected by a hydroxo bridge and a triatomic syn-syn carboxylato bridge in equatorial positions and a halide ion bridge at the axial site. The chromotropism behavior of the complexes, including solvato-, thermo-, and halochromism, were investigated in detail. Their halochromism was investigated in the pH range of 2.0–11.0 by visible absorption spectroscopy. The reversible color variations from blue to colorless are attributable to deprotonation and protonation of the ligands. The complexes show reversible thermochromism in solution due to dissociation and recombination of ligands to copper ions. 相似文献
9.
This paper describes the preparation of [Cu(bh)(2)(H(2)O)(2)](NO(3))(2)], [Cu(ibh)(2)(NO(3))(2)], [Cu(ibh)(2)(H(2)O)(2)](NO(3))(2) and [Cu(iinh)(2)(NO(3))(2)] (bh=benzoyl hydrazine (C(6)H(5)CONHNH(2)); ibh=isonicotinoyl hydrazine (NC(5)H(4)CONHNH(2)); ibh=isopropanone benzoyl hydrazone (C(6)H(5)CONHN=C(CH(3))(2); iinh=isopropanone isonicotinoyl hydrazone (NC(5)H(4)CONHN=C(CH(3))(2)). These copper(II) complexes are characterized by elemental analyses, molar conductances, dehydration studies, ESR, IR and electronic spectral studies. The electronic and ESR spectra indicate that each complex exhibits a six-coordinate tetragonally distorted octahedral geometry in the solid state and in DMSO solution. The ESR spectra of most of the complexes are typically isotropic type at room temperature (300K) in solid state as well as in DMSO solution. However, all the complexes exhibit invariably axial signals at 77K in DMSO solution. The trend g(||)>g( perpendicular)>g(e,) observed in all the complexes suggests the presence of an unpaired electron in the [Formula: see text] orbital of the Cu(II). The bh and inh ligands bond to Cu(II) through the >CO and NH(2) groups whereas, ibh and iinh bond through >CO and >CN groups. The IR spectra of bh and ibh complexes also show HOH stretching and bending modes of coordinated water. 相似文献
10.
Abdel-Nasser M. A. Alaghaz Amani S. Alturiqi Reda A. Ammar Mohamed E. Zayed 《Phosphorus, sulfur, and silicon and the related elements》2019,194(1-2):47-56
The new cyclodiphosph(V)azane derivatives (1,3-dimethyl-2,4-dioxo-2',4'-bis(2,4-bis(dimethylaminopropylimino)cyclodiphosph(V)azane (H2L1) (1,3-dimethyl-2,4-dioxo-2',4'-bis(2,4-bis(dimethylaminoethylimino)cyclodiphosph(V)azane (H2L2) and (1,3-dimethyl-2,4-dioxo-2'-(dimethylaminoethylimino)-4'-(dimethylaminopropyl-imino)cyclodiphosph(V)azane (H2L3) containing four active coordination centers (NNNN) and their Cu(II) complexes have been synthesized and characterized by elemental analyses, spectroscopic methods, molar conductance as well as thermal and magnetic measurements. The UV–Vis and mass spectra of the ligands and their Cu(II) complexes were also recorded. The copper(II) complexes were found to have magnetic moments of 1.58–1.69 B. M. corresponding to one unpaired electron. The possible geometries of the complexes were assigned on the basis of EPR, electronic, and infrared spectral studies. The absence of water molecules in all complexes was supported by thermal studies. All the thermal decomposition processes ended with the formation of CuO. The kinetic and thermodynamic parameters have been calculated. The ligand (H2L3) and its Cu(II) complexes were screened for their anticancer studies against human breast cancer cell lines MCF-7 and minimum inhibitory concentration was calculated. The screening was extended to the antibacterial activity using Kirby–Bauer single disk susceptibility test for all compounds. 相似文献
11.
Cu(II) complexes of acenaphthaquinonemono(4-methylquinolinyl)hydrazone (AMH) of general composition [CuLX2] (whereL=AMH;X=Cl, Br, I, OAc or NO3) with the exception of sulphato complex, where the composition is found to be [CuLSO4]2 have been synthesized and characterized by elemental analyses, magnetic moment measurements, conductivity measurements, IR, electronic and EPR spectral techniques and by thermal analysis. A planar geometry is indicated for all the complexes. TG curves show one step decomposition of complexes and formation of CU2O at the end of the step.One of the author (P.K.S.) is thankful to UGC, New Delhi (India), for providing financial assistance and is also indebted to the Department of Chemistry, University of Delhi, Delhi (India) for providing the necessary laboratory facilities. 相似文献
12.
Chiral and racemic Salen-type Schiff-base ligands (H2L1, H2L2 and H2L3), condensed between D-(+)- and D,L-camphoric diamine (also known as (1R,3S)-1,2,2-trimethylcyclopentane-1,3-diamine) and 2-hydroxybenzaldehyde or 3,5-dibromo-2-hydroxybenzaldehyde with a 1:2 molar ratio, have been synthesized and characterized. A series of new nickel(II), palladium(II) and copper(II) complexes of these chiral and racemic ligands exhibiting different coordination number (4, 5 and 6) have been characterized with the formulae [NiL1]·CH3OH (3), [NiL1]·H2O (4), [NiL2] (5), [PdL2] (6), [Cu2(L2)2(H2O)] (7) and [NiL3(DMF)(H2O)] (8). Different solvent molecules in 3 and 4 (methanol and water molecules) as well as different apical ligands in 7 and 8 (water and DMF molecules) are involved in different O–H···O hydrogen bonding interactions to further stabilize the structures. UV–Vis (UV–Vis), circular dichroism (CD) spectra and thermogravimetric (TG) analyses for the metal complexes have also been carried out. 相似文献
13.
Zong-Hui Jiang Chao-Li Deng Dai-Zheng Liao Shi-Ping Yan Geng-Lin Wang 《Transition Metal Chemistry》1993,18(3):345-347
Summary Four new trinuclear copper(II) complexes, [Cu(phen)-(NBzIm)] (ClO4) (1), [Cu(bpy)(NBzIm)](ClO4) (2), [Cu-(Me2-bpy)(NBzIm)](Ac)·1/2H2O (3) and [Cu(Me2-bpy)-(Im)](ClO4)·1/2H2O (4) (phen = 1, 10-phenanthroline, bpy = 2,2-bipyridine, NBzIm = 6-nitrobenzimidazolate ion, Im=imidazolate ion) have been prepared and characterized by variable temperature magnetic susceptibility measurements. A weak antiferromagnetic spin exchange interaction operates between copper(II) ions, exchange integrals evaluated as J =-23.82 cm-1 for (1); and J=-21.91 cm-1 for (2). 相似文献
14.
Spectral,magnetic, thermal and electrochemical studies on new copper(II) thiosemicarbazone complexes
《Journal of Coordination Chemistry》2012,65(8):713-733
The chelation behavior of some =N(1) and NH(4) thiosemicarbazones towards copper(II) ions has been investigated. The isolated complexes are characterized by elemental analysis, magnetic moment, electronic, IR, ESR and ms spectra, and by thermal and voltammetric measurements. The substituents on =N(1) and/or NH(4) thiosemicarbazones and the log K values of the ligands play an important role in complex formation. The IR spectra showed that the reagents HAT, HAET, HAPT, HApClPT, H2ST and HBT are deprotonated in the complexes and act as mononegative SN donors; H2SET, H2SpClPT, H2HyMBPT and H2HyMBpClPT, as binegative NSO donors while H2SPT is a mononegative NSO donor. The ESR spectra of the complexes are quite similar and exhibit axially symmetric g-tensor parameters with g ‖?>?g ⊥?>?2.0023. The loss of thiol and/or hydroxyl hydrogen was confirmed from potentiometric titrations of the ligands and their copper(II) complexes. The protonation constants of the ligands as well as the stability constants of their Cu(II) complexes were calculated. Thermogravimetric analysis of the complexes suggests different decomposition steps. The Coats–Redfern and Horowitz–Metzger equations have been used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. The redox properties, nature of the electroactive species and the stability of the complexes towards oxidation are strongly dependent on the substituents on the precursor NH(4) thiosemicarbazone. The redox data are discussed in terms of the kinetic parameters and the reaction mechanism. 相似文献
15.
《Journal of Coordination Chemistry》2012,65(8):1320-1326
Unsymmetrically-substituted ruthenium(II) Schiff-base complexes, [Ru(CO)(B)(L x )] [B = PPh3, AsPh3 or Py; L x = dianion of tetradentate unsymmetrical Schiff-base ligand; x = 4–7, L4 = salen-o-hyac, L5 = valen-o-hyac, L6 = salphen-o-hyac, L7 = valen-2-hacn], were prepared and characterized by analytical, IR, electronic, and 1H NMR spectral studies. The new complexes were tested for their catalytic activity towards the oxidation of benzylalcohol to benzaldehyde. 相似文献
16.
17.
M.R. Prathapachandra Kurup Binu VargheseM. Sithambaresan Suja KrishnanS.R. Sheeja Eringathodi Suresh 《Polyhedron》2011,30(1):70-78
An interesting series of nine new copper(II) complexes [Cu2L2(OAc)2]·H2O (1), [CuLNCS]·½H2O (2), [CuLNO3]·½H2O (3), [Cu(HL)Cl2]·H2O (4), [Cu2(HL)2(SO4)2]·4H2O (5), [CuLClO4]·½H2O (6), [CuLBr]·2H2O (7), [CuL2]·H2O (8) and [CuLN3]·CH3OH (9) of 2-benzoylpyridine-N(4)-phenyl semicarbazone (HL) have been synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is inferred from IR spectra. Based on the EPR studies, spin Hamiltonian and bonding parameters have been calculated. The g values, calculated for all the complexes in frozen DMF, indicate the presence of the unpaired electron in the dx2-y2 orbital. The structure of the compound, [Cu2L2(OAc)2] (1a) has been resolved using single crystal X-ray diffraction studies. The crystal structure revealed monoclinic space group P21/n. The coordination geometry about the copper(II) in 1a is distorted square pyramidal with one pyridine nitrogen atom, the imino nitrogen, enolate oxygen and acetate oxygen in the basal plane, an acetate oxygen form adjacent moiety occupies the apical position, serving as a bridge to form a centrosymmetric dimeric structure. 相似文献
18.
《Journal of Coordination Chemistry》2012,65(17):2767-2780
Heterobimetallic complexes of Cu[Tl(SCN)2]2 ·; L (where L?=?acetophenone benzoylhydrazone(abh), acetophenone isonicotinoyl hydrazone(ainh), acetophenone salicyloylhydrazone(ash), acetophenone anthraniloyl hydrazone(aah), p-hydroxy acetophenone benzoylhydrazone (phabh), p-hydroxy acetophenone isonicotinoyl hydrazone (phainh), p-hydroxy acetophenone salicyloylhydrazone(phash) and p-hydroxy acetophenone anthraniloyl hydrazone(phaah) were synthesized and characterized. Electronic spectra and μeff values suggest a distorted octahedral environment around copper(II). SCN groups bridge between two metal centers and the ligands are coordinated through >C=O and >C=N–groups. Thermal studies (TGA and DTA) on Cu[Tl(SCN)2]2?·?ainh indicate multi step decomposition of both endothermic and exothermic nature. ESR data show axial spectra for all the complexes and d x²???y 2 as the ground state. Powder X-ray diffraction parameters for some of the complexes correspond to orthorhombic crystal lattice. The complexes show significant antifungal activity against Rizoctonia sp. and Stemphylium sp. and moderate antibacterial activity against Clostridium sp. and Pseudomonas sp. The activity increases at higher concentration of the compound. 相似文献
19.
20.
Summary It has been found that in the putrescine-copper system several types of complex compounds (MHL,ML,ML
2,ML
2OH) are formed. In thepH range of 7–9, despite a multiple excess of ligand, a precipitation occurs. When adenosine is introduced to the system, the ability to observe the complexation reaction in solution is largely increased, because the additional ligand prevents precipitation. On the basis of computer analysis of potentiometric titration data the stability constants of the compounds have been determined. The coordination mode of the complexes is discussed.
Gleichgewichte und spektroskopische Untersuchungen an Putrescin-Komplexen mit Kupfer(II)
Zusammenfassung Es wurde festgestellt, daß sich im Putrescin-Kupfer System einige Typen von Komplexen bilden (MHL,ML,ML 2 andML 2OH). ImpH-Bereich von 7–9 tritt trotz eines mehrfachen Ligandenüberschusses ein Niederschlag auf. Bei Einführung von Adenosin in das System wird die Beobachtbarkeit der Komplexreaktion verbessert, da der zusätzliche Ligand die Niederschlagsbildung verhindert. Mittels Computeranalyse der potentiometrischen Titrationsdaten wurden die Stabilitätskonstanten der Verbindungen ermittelt. Die Art der Komplexierung wird ebenfalls diskutiert.相似文献