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Reaction of copper(II) perchlorate with pyrazine and pyridine-N-oxide produced the coordination polymer catena-[diaqua-μ-pyrazine-bis(pyridine-N-oxide)copper(II)] perchlorate (1) which was characterized by single-crystal X-ray diffraction, EPR and variable temperature magnetic susceptibility measurements. The compound forms well-isolated linear chains, bridged by pyrazine. EPR studies show a rhombic structure with gave = 2.15. The magnetic data are well described by the uniform Heisenberg chain model giving J/kB = −9.6(1) K and show no signs of inter-chain interactions down to 1.8 K [H = −JΣS1S2]. In the course of the synthesis, the related [tetrakis(pyridine-N-oxide)copper(II)] perchlorate complex (2) was also isolated. X-Ray studies confirm the identity of the compound in comparison to the previous literature. EPR studies indicate a rhombic structure, similar to 1, but variable temperature magnetic susceptibility data show no significant magnetic exchange in agreement with the absence of a superexchange pathway in the crystal.

The coordination chemistry of (diphenyl((5-phenyl-1H-pyrazol-3-yl)methyl) phosphine oxide), 1, was explored. Reacting appropriate equivalents of this ligand and either cobalt perchlorate or MoO2Cl2 results in formation of [Co((C6H5)2POCH2(C3N2H2)(C6H5))2(C4H8O)2][ClO4]2, 2, and MoO2Cl2((C6H5)2POCH2(C3N2H2)(C6H5))(THF), 3. Complexes were characterized by FTIR, NMR, TGA and elemental analyses. Single crystal X-ray spectroscopy reveals octahedral geometries for both compounds. Complex 2 consists of two trans THF ligands in axial positions and two (diphenyl((5-phenyl-1H-pyrazol-3-yl)methyl) phosphine oxide) ligands occupying equatorial positions resulting in an overall octahedral geometry. Two perchlorate counter anions complete the structure. The Co ion resides on an inversion point. THF contains disorder with the four carbon atoms and the major orientation refined to an occupancy of 86.1(9)%. Complex 3 consists of the cis-dioxo MoO2 unit bonded with axial trans-chloride ligands and 1 in the equatorial plane completing the disordered octahedral geometry. A THF ligand is hydrogen bonded to the H-atom on the nitrogen of the pyrazole moiety in ligand 1. DFT calculations based on geometries obtained crystallographically were useful in assigning FTIR peaks and the UV-vis spectra.

During an effort to synthesize the trans-III-copper(II) complex with 1,4,8,11-tetramethyl-pyro-phosphonate-1,4,8,11-tetra-aza-cyclo-tetradecane, using only perchlorate salts, it was noted that the ...

A widely used oxidizing agent in organic chemistry with an assumed structure of “[Ag(py)2]MnO4” and its perchlorate and perrhenate analogues are studied. Their synthesis in pure form is challenging...

Three mononuclear CoIII complexes, [Co(L1tBu)(bdbp)]·2EtOH (1), [Co(L2tBu)(bdbp)] (2) and [Co(L3tBu)2]ClO4 (3) (where H2L1tBu=bis[{6-benzoyl-4-tert-butyl-2-hydroxyphenyl}benzi-midoyl]-1,2-ethane, H2L2tBu= bis[{6-benzoyl-4-tert-butyl-2-hydroxyphenyl}benzimidoyl]-1,3-propane, bdbpH = 4-tert-butyl-2,6-dibenzoylphenolandHL3tBu=2-{N-(4-amino-butyl)benzimidoyl}-6-benzoyl-4-tert-butylphenol),have been synthesized by one-pot condensation involving CoIIperchlorate, ethane-1,2-diamine, propane-1,3-diamine and butane-1,4-diamine.The Schiff bases, H2L2 and HL3, and 1-3have been characterized by elemental analyses, conductivity measurements, mass spectrometry, IR,electronic,1H and 13C NMR spectroscopy, cyclic voltammetry and X-ray crystallography.In 1and 2, the tetradentate ONNO ligand wraps around cobalt in a rare βcis-conformation. Complex 3 possesses a tridentate NNO ligandleading to two seven-membered chelaterings in a fac-CoN4O2 octahedral configuration. Density functional theory (DFT) calculations provide a satisfactory description of the electronic properties of the new compounds. All the complexes are redox active and display the Co(III) – Co(II) couple in the potential range –0.6 to +0.3 V (vs. Ag/AgNO3).Interaction of the complexes with calf thymus DNA (CT-DNA) has been investigated by a spectrophotometric method and cyclic voltammetry. Based on these observations, an intercalative binding mode of DNA has been proposed. The order of their intrinsic DNA-binding constants Kb is Kb (1)

Reaction of the Schiff base, 1-(4-methylimidazol-5-yl) phenylhydrazonopropane-2-one oxime (LH), with copper(II) perchlorate hexahydrate and copper(II) nitrate trihydrate in a 1 : 1 M proportion in methanol affords [Cu2L2(H2O)(ClO4)](ClO4) (1) and [Cu2L2(H2O)2](NO3)2] (2) in moderate yields. Both 1 and 2 have been characterized by elemental analysis, ESI-MS, FT-IR, UV–vis absorption spectroscopy, EPR, electric conductivity, and magnetic susceptibility measurements. The X-ray crystal structures of 1·CH3COCH3 and 2 have been determined. Both compounds are dinuclear copper(II) complexes, with each copper μ2-bridged by two oxime ligands in a μ2-η1,η2 fashion. Variable temperature magnetic studies on 1 and 2 show that both compounds are dominated by an antiferromagnetic coupling through the oxime bridges.

A dicyanoamide-bridged polymeric copper(I/II) complex, [CuII(sal)(bipy)CuI(dca)2]n, was prepared by reaction of 5-methylchlorosalicylaldehyde (Hsal), 2,2′-bipyridine (bipy), sodium dicyanoamide (Nadca), and copper perchlorate in methanol. The complex was characterized by elemental analyses, infrared and electronic spectroscopy, and single-crystal X-ray determination. CuII has a square pyramidal coordination, and CuI has triangular coordination. The complex showed high urease inhibitory activity with IC50 value of 0.16 ± 0.23 μM.

Four mononuclear copper(II) complexes of two new carboxamide derivatives formulated as [Cu(L1)2](ClO4)2 (1a), [Cu(L1)2](NO3)2 (1b), [Cu(L2)2(H2O)2](ClO4)2 (2a), and [Cu(L2)2(H2O)](NO3)2(2b) have been isolated in pure form from the reaction of L1 and L2 [where L1 = N-(furan-2-ylmethyl)-2-pyridinecarboxamide and L2 = N-(thiophen-2-ylmethyl)-2-pyridinecarboxamide] with copper(II) salts of perchlorate and nitrate. All the complexes were characterized by physicochemical and spectroscopic tools along with single-crystal X-ray diffraction studies. The structural analyses showed that 1 is monomeric of square planar geometry with copper(II) chelated by two L1 ligands. Complex 2 differs in coordination geometry, being octahedral and distorted square pyramidal. Two L2 ligands occupy the equatorial positions of the octahedral 2a and the basal sites of the pyramidal 2b, with water molecules that complete the coordination sphere in each case. Electrochemical studies using cyclic voltammetry showed a reversible redox behavior of the copper(II) in 1 and 2. The electronic spectroscopic behavior and the trend of one electron equivalent redox potential corresponding to a CuII/CuI couple have also been confirmed by density functional theory calculations. The spectroscopic and viscosity measurement study in tris–HCl buffer suggested an intercalative interaction of 1a and 2 with calf thymus DNA likely due to the stacking between the non-coordinated furan and thiophene chromophore with the base pairs of DNA.

The reaction of copper(II) perchlorate with the hydrochloride salt of 3,6,9,15-tetra-azabicyclo[9.3.1]penta-deca-1,11,13-triene (L1) in acetonitrile forms two macrocyclic complexes that can be characterized: [L1CuIICl][ClO4] (1) and [L1CuIICl]2[CuCl4] (2). The structural, electronic, and redox properties of these complexes were studied using spectroscopy (EPR and UV–visible) and electrochemistry. In addition, the solid-state structure of 1 was obtained using X-ray diffraction. The copper(II) is five-coordinate ligated by four N-atoms of the macrocycle and a chloride atom. EPR studies of 1 both in DMF and aqueous solution indicate the presence of a single copper(II) species. In contrast, EPR studies of 2 performed in frozen DMF and in the solid-state reveal the presence of two spectroscopically distinct copper(II) complexes assigned as [L1CuIICl]+ and [CuIICl4]2−. Lastly, electrochemical studies demonstrate that both [L1CuIICl]+ and [CuIICl4]2− are redox active. Specifically, the [L1CuIICl]+ undergoes a quasi-reversible Cu(II)/(I) redox reaction in the absence of excess chloride. In the presence of chloride, however, the chemical irreversibility of this couple becomes evident at concentrations of chloride that exceed 50 mM. As a result, the presence of chloride from the chemical equilibrium of this latter species impedes the reversibility of the reduction of [L1CuIICl]+ to [L1CuICl]0.

Copper(II) and cadmium(II) complex of a mono-dibenzofuran derivative of 1,4,7,10-tetraazacyclododecane (cyclen), L1, have been prepared by reaction of the mono-dibenzofuran-substituted cyclen with either copper(II) or cadmium(II) perchlorate in acetonitrile. This yielded the corresponding divalent metal complexes, [Cu(L1)](ClO4)2·H2O (C1) and [Cd(L1)](ClO4)2·H2O (C2), which were isolated as single crystals suitable for X-ray crystallography by diffusing diethyl ether into an acetonitrile solution of each complex. For the copper(II) complex, C1, the X-ray crystal structure revealed a distorted square pyramidal Cu(II) coordination sphere occupied by four amine nitrogens from the cyclen ring and one oxygen from the amide linkage present in L1. On the other hand, the metal center in the cadmium complex is seven coordinate, with two weakly bound acetonitrile molecules occupying two additional coordination sites about the Cd(II) center; these bind cis to the amide oxygen. The coordination geometry is best descr...

Two new mononuclear nickel(II) complexes, [Ni(L)(N3)] (1) and [Ni(L)2(NCS)2] (2), where HL = 2-{[phenyl(pyridin-2-yl)methylidene]amino}benzenethiol, a tridentate Schiff base derived from 2-aminothiophenol and 2-benzoylpyridine, have been prepared and characterized. The syntheses of 1 and 2 have been achieved by the reaction of equimolar amounts of nickel perchlorate and HL in the presence of azide and thiocyanate, respectively. The complexes have been characterized by microanalytical, spectroscopic, single-crystal X-ray diffraction, and other physicochemical studies. Structural studies reveal that 1 and 2 adopt two different geometries, distorted square planar in 1 and octahedral in 2. The two mononuclear complex units are held together by π…π or C–H…π weak intermolecular interactions to develop supramolecular networks in their solid states. The antibacterial activity of 1, 2 and their constituent Schiff base has been tested against some gram(+) and gram(−) bacteria.

An improved synthetic pathway for trans-4,4′-azo-1,2,4-triazole (atrz) was discovered. Pure atrz was obtained directly without any other separation step in an environment friendly process. Treatment of atrz with zinc perchlorate and cupric nitrate led to the isolation of {[Zn(μ-atrz)3](ClO4)2·2H2O}n and {[Cu(μ-atrz)3](NO3)2·2H2O}n, which were well characterized. Their structures were determined by X-ray crystallographic analysis. The calculation results of the formation of {[Zn(μ-atrz)3](ClO4)2 2H2O}n and {[Cu(μ-atrz)3](NO3)2 2H2O}n indicates that the perfect crystal structures in spite of much resistance. A fundamental understanding of the structure and thermal properties involves factors, such as conjugated system, crystal structure, and inorganic metallic compounds that affect their thermal behavior. The high energy of the coordination compounds consists of chemical, electronic, and potential energy. The potential for the improvement of the coordination polymer opens up a new world for research of ener...

New cadmium(II) complexes with phosphine telluride ligands of the type CdX2(R3PTe)n [X = ClO4−, n = 4: R = n-Bu (1), Me2 N (2), C5H10 N (3), C4H8 N (4) or OC4H8 N (5); X = Cl–, n = 2: R = n-Bu (6), Me2 N (7), C5H10 N (8), C4H8 N (9) or OC4H8 N (10)] have been synthesized and characterized by elemental analyses, IR and multinuclear (31P, 125Te, and 113Cd) NMR spectroscopy. In particular, the solution structures of these complexes were confirmed by 113Cd NMR at low temperature, which displays a quintuplet for each of the perchlorate complexes and a triplet for each of the chloride complexes due to coupling with four and two equivalent phosphorus atoms, respectively, indicating a four-coordinate tetrahedral geometry for the metal center. These multiplet features were further accompanied by one bond Te–Cd couplings, clearly showing that the ligand is coordinated to the metal through tellurium. The results are discussed and compared with those obtained for closely related phosphine chalcogenide analogs.

Copper(II) complex of an unsymmetrical tridentate ligand containing oxime, imine, and amine donors was synthesized with a condensation between diacetylmonoxime and ethylenediamine in the presence of copper(II) perchlorate. The complex is characterized by elemental analysis, IR, UV–vis, molar conductance, thermogravimetry, and single-crystal X-ray diffraction. The cation consists of two tridentate 2-(2-aminoethyl)imino-3-butanone oxime with coordination sphere of CuN6 type. The geometry around copper(II) is distorted octahedral with two amine donors, two imine, and two nitrogens of the oxime. Photoluminescence reveals that the complex exhibits strong fluorescent emission in acetonitrile at room temperature. The antibacterial activity of the complex was also studied.

Reaction of 2-(2-pyridinyl)-benzthiazole (Pbt), KSCN, and copper(II)perchlorate hexahydrate in 1 : 2 : 1 molar proportion in dimethyl sulfoxide gives monomeric [Cu(Pbt)(SCN)2DMSO] (1a). In another run, identical proportions of the same reactants in methanol generates a symmetric thiocyanate bridged dimeric copper(II) compound, [Cu2(Pbt)2(SCN)2] (2a), in 72% yield. Both 1a and 2a have been characterized by C, H, and N microanalyses, copper estimation, FTIR, UV–vis spectra, and room temperature magnetic susceptibility measurements. The X-ray crystal structures of 1a and 2a have been determined. Electrochemical studies of 1a and 2a show Cu(II) to Cu(III) oxidation in solution. The thermal behaviors of 1a and 2a have been studied. Bond valence sum method of analysis was performed to assign the oxidation state for each copper center in 1a and 2a. Geometry optimization of 1a, 2a, and their linkage isomers has also been performed at the level of the density functional theory to show that 1a and 2a are the most s...

Treatment of cobalt(II) perchlorate hexahydrate with 2 molar equiv. of 2-aminobenzenethiol (Habt) in acetonitrile afforded a tricationic tricobalt complex, [Co{Co(abt)3}2](ClO4)3·2CH3CN, by aerial oxidation. The molecular structure of the meso (ΔΛ) form of the complex was determined by X-ray crystallography. In the complex cation, the central Co is coordinated by six thiolate groups from two terminal fac(S)-[Co(abt)3] units in an octahedral geometry, forming a linear S-bridged tricobalt structure.

New Schiff base binuclear nickel(II) complexes of N-substituted cyclam derivatives have been prepared by template condensation of 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-l,4,8,11-tetraazacyclo-tetradecane (PC) with appropriate aliphatic diamines and nickel(II) perchlorate. The ligand possesses two coordination sites, an N4O2 amine compartment and N3O2/N4O2 imine compartment. The structural features of the complexes have been confirmed by elemental analysis, IR, UV–Vis, and mass spectra. From the data, octahedral geometry around the two nickels has been suggested. The electrochemical behavior of the complexes show two irreversible one-electron reduction process in the cathodic region and show two irreversible one-electron oxidation process at the anode. Hydrolysis of 4-nitrophenylphosphate using the complexes as catalysts have been carried out. Antimicrobial screening data show good results. The binding of the complexes to calf thymus DNA (CT DNA) has been investigated with absorption and emission spec...

Reaction of Cu(ClO4)2 · 6H2O with pyrazine (pz) and 2,3-dihydroxy pyridine in aqueous solution generates bis(aqua(3-oxy-2-pyridono)copper(II))μ-pyrazine diperchlorate. The compound crystallizes in the triclinic space group P 1. The aqua(3-oxy-2-pyridono)copper(II) units are bridged by pyrazine to form a dimer. These dimers are further bridged by perchlorate to form a structural ladder parallel to the b-axis. Hydrogen bonding interactions and π-stacking of the pyridone rings also provide structural stability to the lattice and provide potential magnetic superexchange pathways. Temperature-dependent magnetic susceptibility data reveal a maximum in χ near 6 K and exhibit a rapid drop in χ at lower temperatures, in agreement with a singlet ground state. The use of several models for fitting the magnetic data gave values of approximately −10 K for the dimer interaction and approximately +1.5 K for the interdimer interaction.

Syntheses, structures, and antimicrobial activities of cobalt(III) complexes with two tetradentate Schiff-base ligands, (BA)2en = bis(benzoylacetone)ethylenediimine dianion and (acac)2en = bis(acetylacetone)ethylenediimine dianion, and two axial pyridines (py) have been investigated. These complexes were characterized by FT-IR, 1H-NMR, UV-Vis spectroscopy, and elemental analysis. The crystal structures of the complexes were determined by X-ray crystallography. Single-crystal X-ray diffraction analyses revealed that both complexes have distorted octahedral environments, Schiff-base ligand coordinates cobalt in four equatorial positions, and the two axial positions are occupied by pyridines. The pyridines and Schiff-base ligands are involved in N–H···O hydrogen bonds with perchlorate. Biological activities of the ligands and metal complexes have been studied on Staphylococcus aureus, Escherichia coli, and Bacillus subtilis by the well diffusion method. The activity data show the metal complexes to be more potent than the parent ligand against two bacterial species.

Interaction of 2-amino-benzothiazole with allyl chloride in ethanol resulted in a mixture of 2-imino-3-allyl-benzothiazole and unreacted 2-amino-benzothiazole. Using such a mixture and copper(II) nitrate trihydrate in ethanol – acetonitrile and alternating-current electrochemical technique, crystals of [Cu(η 2-C10H10SN2)(C7H6SN2)NO3] (1) π-complex, containing 2-imino-3-allyl-benzothiazole and 2-amino-benzothiazole coordinated to copper, have been obtained. The same procedure, starting from copper(II) perchlorate hexahydrate, performed in ethanol, led to formation of [Cu(C7H6SN2)2]ClO4 (2) σ-compound. Both compounds were structurally characterized. In the structure 1, 2-imino-3-allyl-benzothiazole is a chelate, bound to metal by C=C-bond of the allyl and nitrogen of the imino group. Another nitrogen from the thiazole core of 2-amino-benzothiazole and oxygen from complete a distorted trigonal-pyramidal environment of copper. [Cu(η 2-C10H10SN2)(C7H6SN2)NO3] building blocks are interconnected into infinite ch...

Compounds [CdLCl2] n (1) and {[Cd(L)2(ClO4)]·ClO4} n (2), where L = 1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, have been synthesized by hydrothermal method, and characterized by element analysis, IR spectra, Powder XRD, and X-ray crystallographic diffraction. Cd(II) in 1 and 2 are both trigonal bipyramidal. Different cadmium salts of chloride and perchlorate lead to different configurations of [Cd2L2]2+, trans-form in 1 but trans and cis-forms in 2. The 1-D beaded chains of 1 are further linked to generate a 3-D supramolecular architecture by strong π–π stacking interactions as well as intermolecular C–H ··· Cl hydrogen bonds. In 2, the 1-D beaded chains are further assembled by intermolecular C–H ··· O hydrogen bonds to form a 2-D layer. Solid-state fluorescent properties of 1 and 2 were investigated at room temperature.

[Cu2(H4L)(OCH3)(H2O)] · 2MeOH (1) has been synthesized from the reaction of 2-hydroxy-5-methylisophthalaldehyde, tris(hydroxymethyl)aminomethane and copper(II) perchlorate in methanol with the Schiff-base polyhydroxyl ligand (H4L)3− formed in situ. Single-crystal X-ray structure analysis of 1 reveals a binuclear structure with Cu(II) asymmetrically bridged by a methoxo and a phenoxo group with Cu–O–Cu bridging angles of 102.93(7)° and 100.17(7)°, respectively. The binuclear Cu(II) moieties utilize the coordinated and noncoordinated alkoxyl groups for formation of intermolecular hydrogen bonds, thus affording a 3-D supramolecular structure. Variable temperature magnetic measurements reveal strong antiferromagnetic coupling in 1 with the 2J-value of −729 cm−1, which was mediated cooperatively by the methoxo and phenoxo bridges. Magneto-structural correlations are discussed based on the crystal structure.

Three zinc complexes based on 2,6-bis(N-2-pyridylmethyl)formimidoyl-4-methylphenolate (HL) by employing Zn(ClO4)2, Zn(CH3COO)2, and ZnCl2 have been synthesized and investigated as functional models of phosphoesterases. The molecular structure of [{Zn2L(µ 3-OH)(H2O)}2](ClO4)4 (1) obtained by reacting zinc perchlorate with HL was determined by X-ray diffraction analysis, revealing a tetranuclear species with four zinc centers and two ligands. Two zinc ions are accommodated within the two compartments of each ligand and are bridged by an additional hydroxide leading to Zn–Zn distances of 3.1235(9) and 3.1268(9) A, respectively. The hydroxide is involved in an additional bridge to the second LZn2 moiety forming a µ 3-OH. A water molecule is coordinated to two of the four zinc ions. The occurrence of a hydroxide group and of a coordinated water is relevant to the structure found in the native enzyme. The hydrolysis of the phosphoester bis(p-nitrophenol)phosphate ester (BNPP) in a mixture of DMSO and water at 5...

A series of macrocyclic complexes, [Cu(TAAP)]X2, X = ClO4 and CH3COO; [Cu(TAAP)X]X, X = NO3, Cl, and Br, have been synthesized by self-condensation of 5-amino-3-methyl-l-phenylpyrazole-4-carbaldehyde (AMPC) in the presence of copper(II). Elemental analyses and conductivity measurements confirm the stoichiometry of the ligand and complexes, while the characteristic absorption bands in IR spectra confirmed the formation of ligand framework around copper. Square-pyramidal and square-planar stereochemistries have been proposed for the five-coordinate (nitrato and halogeno) and four-coordinate (perchlorate and acetate) complexes. The electrochemical properties and thermal behaviors have been studied by cyclic voltammetry and TGA. Mimetics of antioxidant enzymes such as superoxide dismutase (SOD) and catalase demonstrated that there is a correlation between the observed redox properties and the SOD and catalase biomimetic catalytic activities of the copper(II) complexes.

Template reaction of copper(II) nitrate with N-(2-aminoethyl)-1,3-diaminopropane and formaldehyde yields a macrocyclic copper(II) complex of 1,3,6,10,12,15-hexaazatricyclo[13.3.1.16,10]eicosane (L), [CuL(NO3)2] (1). Replacement of nitrate with perchlorate gives [CuL(ClO4)2] (2). These complexes have been characterized by FT-IR and Raman spectroscopies, electronic absorption, cyclic voltammetry, and X-ray crystallography. The crystal structure of 1 shows that copper has distorted octahedral geometry with two secondary and two tertiary amines of the macrocycle and two oxygen atoms from nitrate coordinating the axial positions. The copper in 2 has the same geometry with axial positions occupied by one oxygen atom of perchlorate. Copper lies on the plane of four coordinated nitrogen atoms and there is no rms deviation from this plane. Cyclic voltammetry of 1 and 2 gives two one-electron waves corresponding to CuII/CuIII (−0.75, −0.72) and CuII/CuI (0.48, 0.24) processes. For understanding of geometry paramete...

A new oxamido-bridged dinuclear compound [Cu2(µ-pmox)(DMF)4] · 2ClO4 (1) (H2pmox = N,N′-bis-(2-methylpyridyl)oxalamide, DMF = dimethylformamide) was synthesized and structurally characterized. The five-coordinate Cu(II) is bridged by oxamido groups and further cross-linked by C–H···O hydrogen bonds between the uncoordinated oxygen of perchlorate and methyl of DMF. The complex was also characterized by infrared spectroscopy and magnetic measurement. The copper complex exhibits strong antiferromagnetic interactions via the trans oxamido bridge with J of −414 cm−1, where J is the exchange parameter in the isotropic Hamiltonian H = −JS1S2.

Two new potentially hexadentate Schiff bases, [H2L1] and [H2L2], were prepared by condensation of 2-(3-(2-aminophenoxy)naphthalen-2-yloxy)benzenamine with 3,5-di-tert-butyl-2-hydroxy benzaldehyde and o-vanillin, respectively. Reaction of these ligands with cobalt(II) chloride, copper(II) perchlorate, and zinc(II) nitrate gave complexes ML. The ligands and their complexes have been characterized by a variety of physico-chemical techniques. The solid and solution state investigations show that the complexes are neutral. Molecular structures of [CuL1], [CoL1] · C7H8, and [ZnL2] · CH3CN, which have been determined by single-crystal X-ray diffraction, indicate that [CuL1] and [ZnL2] · CH3CN display distorted square planar and distorted trigonal-bipyramidal geometry, respectively; the geometry around cobalt in [CoL1] · C7H8 is almost exactly between trigonal bipyramidal and square pyramidal. The synthesized ligands and their complexes were screened for their antibacterial activities against eight bacterial stra...

The reaction of pyridine-2,6-dicarbaldehyde or 2,6-diacetylpyridine with 1,2-bis(o-aminophenylthio)ethane (1) in acetonitrile in the presence of stoichiometric amounts of iron(II) perchlorate gave the complexes [(pyN3S2)FeII(ClO4)2] (4) and [(pyN3Me2S2)FeII(ClO4)2] (5) of the 15-membered N3S2 macrocyclic ligands, pyN3S2 = {6,7-dihydro-15,19-nitrilobenzo(e,p)(1,4,7,15)dithiadiazacyclo-heptadecine-N,N′,N″,S,S′} and pyN3Me2S2 = {6,7-dihydro-16,18-dimethyl-15,19-nitrilobenzo(e,p)(1,4,7,15)dithiadiazacyclo-heptadecine-N,N′,N″,S,S′}, respectively. Physical measurements led to the conclusion that these complexes contained seven-coordinate iron(II) and a single-crystal X-ray examination of 4 confirmed this. Coordination of the Fe(II) center in 4 is best described as distorted pentagonal-bipyramidal with the three nitrogen atoms and two sulfur donors of the macrocycle defining the pentagonal plane and the perchlorate ions occupying axial positions. Room temperature (293 K) magnetic moments of 4 and 5 (μ eff = 4.9...

Five new complexes of bis(1-amidino-O-alkylurea)Cu(II)vanadate where alkyl = methyl, ethyl, n-propyl, n-butyl or i-butyl have been synthesized by reaction of ammonium metavanadate with bis(1-amidino-O-alkylurea)Cu(II)perchlorate complexes. Electron paramagnetic resonance (EPR) spectra of bis(1-amidino-O-n-propylurea)Cu(II)vanadate (1), bis(1-amidino-O-n-butylurea)Cu(II)vanadate (2) and bis(1-amidino-O-i-butylurea)Cu(II)vanadate (3) gave half-field signal (ΔM s = ±2) ca 1623G, in addition to fine structure due to zero field splitting (ZFS) characteristics of the S = 1 system. From the observed ZFS the average Cu–Cu distance was estimated. The isotropic exchange constant J was evaluated by recording EPR spectra at different temperatures. The photoacoustic signal of the complexes indicated square-planar geometry around Cu2+. X-ray powder diffraction studies on 2 suggested orthorhombic structure with unit cell dimensions a = 21.11 A, b = 24.11 A, c = 27.11 A, α = β = γ = 90°. The crystal structure of bis(1-am...

Two new transition metal coordination polymers, [Zn(abz)(bipy)](ClO4) (1) and [Mn(bipy)5(H2O)6](ClO4)2 · 2(abz) · 2(H2O) (2) (bipy = 4,4′-bipyridine, abz = 3-aminobenzoate), were prepared and characterized by elemental analysis, FTIR spectroscopy, and single-crystal X-ray diffraction. Complex 1 is a 2-D-layered network with a (4,4) net built up by bipy and 3-aminobenzoate ligands connecting two zinc nodes. Complex 2 is a 3-D supramolecular grid network constructed from close stacking bipy ligands of H-type cation units with large cavities hosting 3-aminobenzoate, perchlorate ions, and water. Solid state photoluminescence for 1 was also investigated.

Reaction of Co(ClO4)2 · 6H2O with N,N-diisopropylisonicotinamide (L) has yielded a 1-D coordination polymer [{Co(L)2(H2O)2}(ClO4)2(CH3COCH3)2(H2O)2] n (1). Complex 1 has been characterized by infrared (IR) and UV-Vis spectroscopies, thermal analysis, and single crystal X-ray diffraction techniques. The structure has alternate arrangement of parallel 1-D cationic metal-ligand chains and H-bonded anionic chains containing perchlorate, acetone and water in the lattice. Further hydrogen bonding among both chains leads to formation of 2-D networks along almost perpendicular planes. Interpenetrations of such perpendicular 2-D sheets create a 3-D supramolecular structure.

A new series of complexes of transition metal (Cu, Zn, Ni) perchlorate with imidazole have been synthesized and characterized by elemental analysis, infrared (IR), UV-Vis spectroscopy, and single-crystal X-ray diffraction. Based on elemental and spectral data, the complexes are M(C3H4N2) x (ClO4)2 (M = Cu, Zn, x = 4; M = Ni, x = 6; C3H4N2 = imidazole). The crystal structures of Cu(C3H4N2)4(ClO4)2 (1) and Zn(C3H4N2)4(ClO4)2 (2) show metals surrounded by four nitrogens of imidazole, while the nickel complex Ni(C3H4N2)6(ClO4)2 (3) has six nitrogens of imidazole. Intra- and inter-molecular hydrogen bonds exist between hydrogen of imidazole and oxygen of perchlorate. The thermal stabilities of 1, 2, and 3 at different heating rates (β = 5°C min−1, 10°C min−1, and 15°C min−1) show that all the complexes exhibit two thermal decomposition stages; the sequence of thermal stability is 2 > 1 > 3. 1, 2, 3, and imidazole display DNA binding ability, ascertained by UV-Vis titration.

Three new mononuclear copper(II) complexes, [CuL(2-fca)(CH3OH)]ClO4 · CH3OH (1), [CuL(m-nba)(CH3OH)]ClO4 (2), and [CuL(pic)(ClO4)] · CH3OH (3), were synthesized and structurally characterized, where L is 2,6-bis(benzimidazol-2-yl)pyridine, while 2-fca, m-nba, and pic are the anions of 2-furoic acid, m-nitrobenzoic acid, and picolinic acid, respectively. All of them were characterized by elemental analysis, infrared, UV-Vis, and X-ray crystallography. In 1 and 2, the Cu(II) resides within a distorted square-pyramidal N3O2 coordination sphere with three nitrogens of L, one carboxylate oxygen, and one methanol. In 3, Cu(II) is coordinated with three nitrogens of L, one nitrogen and one oxygen of picolinate, and one oxygen of perchlorate in a distorted octahedral geometry. Two molecules of 1, 2, and 3 are interacted by intermolecular hydrogen-bonding interactions and strong π–π stacking interactions to form a dinuclear structural unit. The dinuclear units are further connected by H-bonds via perchlorate or la...

A new series of acyclic mononuclear copper(II) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and copper perchlorate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show a d–d transition in the range 500–800 nm, electrochemical studies of the complexes show irreversible one-electron-reduction process around −1.10 to −1.60 V. The reduction potential of the mononuclear copper(II) complexes shifts toward anodic direction upon increasing the chain length of the imine compartment. ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry, with nuclear hyperfine spin 3/2. The copper(II) complexes show a normal room temperature magnetic moment value μ eff = 1.72–1.76 BM, close to the spin-only value of 1.73 BM. Ele...

Both bis- and tetrakis-substituted 2,2′-bipyridine complexes of lead(II), [Pb(bpy)2](PF6)2 and [Pb(bpy)4](PF6)2 · bpy, respectively, have been characterized by X-ray crystallography as hexafluorophosphate salts when three equivalents of bipyridine is combined with Pb(NO3)2 in aqueous solution prior to metathesis. The tetrakis-substituted product, [Pb(bpy)4](PF6)2 · bpy, shows an unusual combination of intramolecular and intermolecular π-stacking of two of the bipyridine ligands throughout the crystal. Incomplete metathesis also produces a catenated, mixed-anion complex, [Pb(bpy)2(µ-NO3)](PF6), where the nitrate bridges lead(II) metal centers to form a 1-D coordination polymer. If metathesis is carried out using perchlorate, a known [Pb(bpy)2](ClO4)2 analog is produced along with [bpyH](ClO4), which has not been previously characterized by X-ray crystallography.

The kinetics of the interaction of DL-penicillamine with cis-[Pt(cis-dach)(OH2)2]2+ has been studied spectrophotometrically as a function of [cis-[Pt(cis-dach)(OH2)2]2+], [DL-penicillamine], and temperature at a particular pH (4.0), where the complex exists predominantly as the diaqua species and DL-penicillamine as a zwitterion. The substitution reaction proceeds via rapid outer sphere association, followed by two slow consecutive steps. The first is the conversion of title complex into an inner sphere complex and the second is the slower chelation step whereby another aqua ligand is replaced. The association equilibrium constant (K E) for the outer sphere complex formation has been evaluated together with rate constant for two subsequent steps. The activation parameters for both steps have been evaluated using the Eyring equation: ( = 36 ± 4 kJ mol−1, = −175 ± 12 JK−1 mol−1 and = 44 ± 1 kJ mol−1, = −189 ± 3 JK−1 mol−1). The low enthalpy of activation and large negative value of entropy of activation are...

A binuclear copper(II) complex, [Cu2(μ 1,3-N3)(N3)(pmp)2(ClO4)]ClO4 (pmp = 2-((pyridin-2-yl) methoxy)-1,10-phenanthroline), was synthesized with a single azide as end-to-end bridge ligand, and pmp and perchlorate as ligands. In the crystal, Cu(II) is in a distorted square pyramidal geometry, and a single azide bridges equatorial-axial linking two Cu(II) ions with separation of 5.851 A. There are π−π stacking interactions involving 1,10-phenanthroline rings. The variable-temperature (2–300 K) magnetic susceptibilities were analyzed using a binuclear Cu(II) magnetic formula and it indicates that there is a very weak ferromagnetic coupling with 2J = 2.82 cm−1.

A series of unsymmetrical dicompartmental binuclear copper(II) complexes have been prepared by Schiff-base condensation of 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-l,4,8,11-tetraazacyclotetradecane (L) with aliphatic and aromatic diamines, copper(II) perchlorate and triethylamine. The complexes were characterized by elemental and spectral analysis. Electronic spectra of the complexes show d–d transitions in the range 663–786 nm. Electrochemical studies of the complexes in DMF show two irreversible one electron reduction processes = −0.62 to −0.77 V and = −0.94 to −1.17 V. Cryomagnetic investigations of the binuclear complexes show −2J values in the range of 154 to 236 cm−1. The rate constants for hydrolysis of 4-nitrophenylphosphate are in the range of 2.27 × 10−2 to 9.21 × 10−2 min−1 and for catecholase activity in the range of 3.06 × 10−2 to 8.35 × 10−2 min−1. All the complexes were screened for antifungal and antibacterial activity.

[Mn(tfbdc)(MeOH)4] was synthesized by reaction of tetrafluoroterephthalatic acid with manganese(II) perchlorate hexahydrate in methanol. The complex was characterized by elemental analysis, IR spectra, magnetism, and X-ray single crystal structure analysis. This complex crystallizes in the monoclinic system with space group C2/c. Mn(II) has a distorted octahedral geometry coordinated by two oxygens from two tetrafluoroterephthalate (tfbdc) and four MeOH molecules. Each tfbdc ligand bridges two Mn(II) ions in end-to-end fashion, forming a zigzag chain. These chains are connected by hydrogen bonds, forming a 2-D supramolecular network. Magnetic susceptibility data from 300–1.8 K show that there is a weak antiferromagnetic exchange between Manganese(II) ions.

A mononuclear Cu(II) compound [Cu(OAc)(2,2′-dypam)2](ClO4) (1), where HOAc and 2,2′-dypam are, respectively, acetic acid and 2,2′-dipyridylamine, has been synthesized and characterized by single crystal X-ray diffraction analysis. The cations of 1 link by N–H ··· O hydrogen bonds to form infinite 1-D zig-zag chains, which run along the b axis. Two adjacent chains along the c axis are joined by C–H ··· O hydrogen bonds to form a 2-D network. These 2-D layers are further bridged by perchlorate anions via weak anion-π interactions that act as a supramolecular glue to build the 3-D supramolecular network. Variable temperature (1.7–300 K) magnetic measurements revealed very weak intermolecular antiferromagnetic interactions at temperatures below 20 K between Cu(II) ions mediated by hydrogen bonds, C–H ··· π and π ··· π interactions. At temperatures ≥20 K, susceptibility data corresponds to isolated Cu(II) ions, indicating that the weak interactions affect the magnetism of 1 only at very low temperatures.

A new pyrazolate-bridged quasi-hexacopper(II) complex [Cu3(μ3-OH)(μ-pz)3(pzH)3 (μ3-ClO4)]2(μ-ClO4)2 · (CH3OH)0.33 · (C2H5OH)0.66 · H2O (pz = pyrazolate), 1, has been isolated and characterized by single crystal X-ray diffraction, elemental analysis, IR and UV–visible spectra and magnetic susceptibilities. The complex crystallizes in the orthorhombic system, space group Pbca ( , No. 61), a = 17.771(4) A, b = 16.143(4) A, c = 25.502(6) A, V = 7316(3) A3, Z = 8, F(000) = 3521, D c = 1.576 g cm−3. The structure of 1 consists of two [Cu3(μ3-OH)(μ-pz)3(pzH)3(μ3-ClO4)]2+ trimers, which are weakly bridged by two perchlorate ions via centrosymmetric operation to form a trigonal prism with the six Cu atoms at six vertexes. Magnetic measurements were performed in the temperature range 2–300 K. The experimental data above 9 K could be satisfactorily reproduced by using an isotropic exchange model, (1), with parameters of J = −241.91 cm−1, ZJ′ = −23.04 cm−1 and g = 2.07, showing strong antiferromagnetic behaviors in C...

Condensation of two equivalents of isonicotinic acid with 1,8-dihydroxyanthraquinone forms 1,8-bis(isonicotinyloxy)anthracene-9,10-dione (1), a potential bridging diester ligand. Complexation reactions between 1 and Co(II) and Ni(II) perchlorate hexahydrate salts produce 2 : 1 ligand : metal monomeric complexes. One nicotinic nitrogen is bonded to a metal center while the second ‘free’ isonicotinic nitrogen is hydrogen bonded to water molecules, present from the hydrated salts used in the synthesis, ligated to the same metal center.

The perchlorate salts of two new ruthenium(II) complexes incorporating 2-(2′-pyridyl)naphthoimidazole are synthesized in good yield. Complexes [Ru(phen)2(PYNI)]2+ (phen = 1,10-phenanthroline) 1 and [Ru(dmp)2(PYNI)]2+ (dmp = 2,9-dimethyl-1,10-phenanthroline, PYNI = 2-(2′-pyridyl)naphthoimidazole) 2 are fully characterized by elemental analysis, FAB-MS, ES-MS, 1H NMR and cyclic voltammetric methods. The DNA-binding behavior of the complexes have been studied by spectroscopic titration, viscosity measurements and thermal denaturation. Absorption titration and thermal denaturation studies reveal that these complexes are moderately strong binders of calf-thymus DNA (CT-DNA), with their binding constants spanning the range (2.73–5.35) × 104 M−1. The experimental results show that 1 interacts with calf thymus DNA (CT-DNA) by intercalative mode, while 2 binds to CT-DNA by partial intercalation.

A 1D complex [{[Cu2([12]aneN3)2(p-paa)(H2O)2](ClO4)2}[Cu2([12]aneN3)2(p-paa)2]] n ([12]aneN3 = 1,5,9-triazacyclododecane, p-paa = p-benzenebicarboxylate) has been synthesized and structurally characterized. The complex contains two different binuclear copper(II) moieties. One part includes a binuclear copper(II) unit and non-coordinated perchlorate anions. A neutral binuclear copper(II) part which forms a zigzag chain structure via the bridging p-paa ligand completes the unit-cell. Elemental analysis, IR, UV-Vis spectra and magnetic properties for the complex have also been determined. Magnetic susceptibilities in the solid state are measured over the temperature range from 77 to 300 K, showing a weak antiferromagnetic coupling with a best fit J 1 = −3.09 cm−1, J 2 = −5.279 cm−1, g = 2.099 and R = 1.226 × 10−5.

Five- and six-coordinate, α-[Ni(tet-b)(Cl)](ClO4) (1) and α-[Ni(tet-b)(en)](ClO4)2 (2) (tet-b = C-racemic-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) complexes have been synthesized and isolated from the reactions of α-[Ni(tet-b)](ClO4)2, which has trans-V (1R,4R,8R,11R,7S,14S or 1S,4S,8S,11S,7R,14R) conformation, with t-Bu4NCl and ethylenediamine (en), respectively. The complexes have been characterized by X-ray crystallography. The crystal structure of 1 shows a distorted trigonal bipyramidal (TBP) coordination geometry composed of four nitrogen atoms from tet-b and a chloro group with an N4Cl chromophore about the nickel(II) ion. The complex cations of 1 are assembled by the perchlorate ions via N–H ··· O hydrogen bonding to form 1-D zigzag chains along the [001] direction. The chains are linked through intermolecular hydrogen bonding where the coordinated chloro group of the complex cation forms two-center double hydrogen bonds with the adjacent N–H groups of the macrocyclic ligand al...

Optically pure enantiomers of pipecolic acid are conveniently prepared in high yield by reacting the racemate with Λ-β-[Co(R,R-picchxn)Cl2]+ (picchxn = N,N′-di(2-picolyl)1,2-diaminocyclohexane) and crystallization of pure internal diastereoisomers as perchlorate salts. Subsequent reactions give the free acid of either hand. The stereochemical course of the resolution is established unambiguously by a single-crystal X-ray analysis of one intermediate and a combination of CD and 1H NMR measurements.

Complexes involving the perchlorate, chloride, bromide or iodide salts of the heavy group 2 elements, calcium, strontium or barium, and either 15-crown-5 or 18-crown-6 have been synthesized and their X-ray crystal structures determined. A variety of coordination modes are presented between the crown ether and metal ions.

Reactions of 2,2′-bipyridine (2,2′-bipy) with cadmium perchlorate in a ratio of M : L 1 : 2 and 1 : 3 give complexes with stoichiometry [Cd(2,2′-bipy)2(H2O)(ClO4)]ClO4 (1) and [Cd(2,2′-bipy)3](ClO4)2 · 0.5 2,2′-bipy (2), respectively. The new complexes were characterized by elemental analyses and IR-, 1H-, 13C-NMR spectroscopy. The crystal structures of the [Cd(2,2′-bipy)2(H2O)(ClO4)]ClO4 (1) and [Cd(2,2′-bipy)3](ClO4)2 · 0.5 2,2′-bipy (2) were determined by X-ray crystallography and the their thermal behavior studied by TG and DTA. Complexes 1 and 2 are built up of monomeric [Cd(2,2′-bipy)2(H2O)(ClO4)]ClO4 and [Cd(2,2′-bipy)3](ClO4)2 · 0.5 2,2′-bipy with Cd2+ coordination, CdN4OwaterOperchlorate and CdN6, respectively. There are classical O–H ··· Operchlorate hydrogen bonds in complex 1 and non-classical C–H ··· Operchlorate approaches in complex 2. The monomeric units of 1 and 2 grow into dimeric and one-dimensional units by packing via hydrogen bonding.

A new μ-oxamido-bridged dicopper(II) complex, [Cu2(heap)](ClO4)2 · 2H2O [H2heap = N,N′-bis(N- hydroxyethylaminopropyl)oxamido], has been synthesized and structurally characterized by elemental analyses, molar conductance, IR and single-crystal X-ray diffraction. The single crystal X-ray analysis reveals that the asymmetric unit of the complex is composed of half a binuclear cation [Cu2(heap)]2+, one perchlorate anion, and one lattice water molecule. Each copper(II) atom is tetracoordinate in a distorted square-planar geometry and the bridging ligand (H2heap) adopts the trans conformation with an inversion centre at the middle of the C2–C2i bond. The structure cohesion is ensured by hydrogen bonding interactions, which form a two-dimensional supramolecular framework. The antibacterial assay indicates that the complex showed better activity than the ligand.