Syntheses,structures and luminescent properties of four copper(I) cyanide coordination polymers based on 2-(n-pyridyl)benzimidazole ligands (n = 2, 3, 4)

Four copper(I) cyanide coordination polymers containing 2-(n-pyridyl)benzimidazole ligands, namely [Cu₂(CN)(2-PyBIm)]_n (1), [Cu₂(CN)₂(3-PyHBIm)]_n (2), {[Cu₃(CN)₃(4-PyHBIm)₄] · 2H₂O}_n (3) and [Cu₅(CN)₃(4-PyBIm)₂]_n (4), have been synthesized and characterized by X-ray crystallography. Complex 1 is a one-dimension coordination polymer in which 2-(2-pyridyl)benzimidazole is deprotonated and adopts a bridging tridentate coordination mode. Complex 2 has ladder-like structure in which 2-(3-pyridyl)benzimidazole does not deprotonate and acts as a bidentate bridge. Complex 3 displays a saddle-shaped helical chain constructed through μ₂-cyanide group and the outstretched neutral 2-(4-pyridyl)benzimidazole monodentate ligand. Complex 4 shows two-dimension layer polymeric structure in which deprotonated 2-(4-pyridyl)benzimidazole acts as a tridentate bridging ligand. The cyanide groups in four complexes all act as bidentate bridging ligands. These complexes are thermal stable and display luminescence in the solid states.     

Methanolysis of Pyrazinecarbonitrile in the Coordination Sphere of Copper(II). The Crystal Structure of Dichlorobis(O-Methylpyrazinecarboximidate)-Copper(II) Dihydrate

Abstract

Reaction of pyrazinecarbonitrile (pz-CN) with copper(II) in methanol solution led to formation of solid complexes containing O-methylpyrazinecarboximidate (pz-C(NH)OMe) as a ligand. The analogous reaction of pyrazinecarbonitrile in ethanol led to isolation of solid complexes containing unchanged pz-CN. Six novel copper(II) compounds have been obtained under various reaction conditions. Their stereochemistry and the mode of ligand coordination has been determined by spectroscopic and conductometric measurements. Moreover, the crystal structure of the complex [CuCl₂(O-methylpyrazinecarboximidate)₂]. 2H₂O has been determined by X-ray diffraction techniques.     

Short Communication: Crystal Structure of a Molecular Complex from Native β-Cyclodextrin and Copper(II) Chloride

Reaction of β-cyclodextrin (β-CD) with CuCl₂ in neutral aqueous solutions gave a stable molecular complex without any side-arm support. The X-ray crystallographic analysis clarified that the copper ion was located at the bottom of the primary-hydroxy side as a CuCl₂(H₂O)₂ form. Hydrogen bonds were found between the Cl and H₂O ligands and β-CD hydroxy and ether groups. The copper ion is axially coordinated with a hydroxy group of a neighboring β-CD molecule, giving a one-dimensional β-CD/CuCl₂ array.     

Solvent effect on CuCl2-pyridine derivative complexes: UV-VIS and E.S.R. study of the CuCl2-2,4-dimethylpyridine-solvent systems

Summary The electronic (400–800 nm; 298.2 K) and E.S.R. spectra (298 K; 77 K) have been measured for CuCl₂-2,4-dimethylpyridine(2,4-Me ₂ py)-solvent systems (solvents: aliphatic and aromatic hydrocarbons, carbon tetrachloride, chloroform, 1,1,2,2-tetrachloroethane). In all the media CuCl₂ forms electrically neutral strongly distorted six-coordinated complexes, the extent of tetragonality being greater than for analogous complexes with non-a-substituted pyridines. In contrast to aliphatic and aromatic hydrocarbons protic solvents and, unexpectedly, aprotic carbon tetrachloride solvate the CuCl₂-Me ₂ py complex comparatively strongly, most probably through interactions with the chlorine ligand. The results for 2,4-Me ₂ py were compared with those for pyridine, 4-ethylpyridine and isoquinoline and discussed in terms of steric effects on solvation. In particular,a-substitution seems to hinder the solvation of the complex by the amine.

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Lösungsmitteleinfluß auf den Koordinationszustand des CuCl₂ in Lösungen. Elektronen- und EPR-Spektren der CuCl₂-2,4-Dimethylpyridin-nichtwäßrigen Lösungsmittel-Systeme

Zusammenfassung Es wurden die Absorptions-Elektronenspektren (400–800 nm; 298.2 K) und EPR-Spektren (298 K; 77 K) verschiedener CuCl₂-2,4-Dimethylpyridin(2,4-Me ₂ py)-Lösungsmittel(L)-Systeme gemessen und mit analogen CuCl₂-Pyridinbasen-L-Systemen verglichen (L=aliphatische und aromatische Kohlenwasserstoffe, Chloroform, Tetrachloromethan, 1,1,2,2-Tetrachlorethylen). In allen Lösungen bildet CuCl₂ mit Pyridinbasen neutrale, stark verzerrt oktaedrische monomere Komplexe. Die Verzerrung nimmt mita-Substitution zu. Bemerkenswert ist, daß CCl₄ einen Mediumeffekt zeigt, der demjenigen der protischen Lösungsmitteln ähnlich ist; er solvatiert die Komplexe verhältnismäßig stark, möglicherweise an den Chloridliganden. Die Komplexe vona-substituierten Phyridinbasen sind gegenüber Solvatation weniger empfindlich als die übrigen.

     

Synthesis and electrocatalytic properties of a dinuclear copper(II) complex for generating hydrogen from acetic acid or water

The reaction of CuCl₂?2H₂O and a tetradentate amine phenol ligand affords a dinuclear Cu(II) complex, 1, a new molecular electrocatalyst, whose structure has been determined by X-ray crystallography. Electrochemical studies show that 1 can efficiently produce hydrogen from acetic acid with a turnover frequency (TOF) of 50.1 (in DMF) or from water with a TOF of 104.3 (pH 7.0) moles of hydrogen per mole of catalyst per hour.     

Synthesis,spectroscopic characterization,X-ray structure and DFT calculations of copper(II) complex with 2-(2-pyridyl)benzimidazole

The reaction of copper(II) nitrate trihydrate and 2-(2-pyridyl)benzimidazole (pybzim) leads to [Cu(pybzim)₂(NO₃)](NO₃). The compound has been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The electronic structure of the [Cu(pybzim)₂(NO₃)]⁺ cation has been calculated with the density functional theory (DFT) method. The spin-allowed doublet–doublet electronic transitions of [Cu(pybzim)₂(NO₃)]⁺ have been calculated with the time-dependent DFT method, and the UV–Vis spectrum of the title compound has been discussed on this basis.     

CuCl2和HY分子筛的表面反应及Cu/Y分子筛的制备及其催化甲醇氧化羰基化

以CuCl₂为前驱物与HY分子筛进行固相离子交换制备了Cu/Y催化剂,采用热重方法研究了CuCl₂与HY分子筛的表面固相离子交换反应,结合活性测试表明催化剂中高度分散的CuCl和离子交换形式的Cu⁺物种是甲醇氧化羰基化合成碳酸二甲酯的催化活性中心。X射线光电子能谱表征和元素分析结果表明,活性金属Cu主要以CuCl形式存在于分子筛外表面,而在分子筛笼内则以交换的Cu⁺和少量吸附的CuCl形式存在。与以CuCl为交换铜源所制催化剂相比,以CuCl₂为铜源制备的催化剂Cu含量低,催化活性更高。     

Syntheses and structural characterization of six ionic salts based on bis(benzimidazole)/bis(imidazole) and perchlorometallates of Zn and Cu

Six salts, ([(H₂L1)(ZnCl₄)] (1) (L1 = 1,1′-bis(benzimidazolyl)methane), [(H₂L1)(CuCl₄)]·H₂O (2), [(H₂L2)(ZnCl₄)] (3) (L2 = 1-(3-(1H-benzimidazol-1-yl)propyl)-1H-benzimidazole), [( H₂L2)(CuCl₄)] (4), [(H₂L3)(CuCl₄)]·H₂O (5) (L3 = 1- (4-(1H-benzimidazol-1-yl)butyl)-1H-benzimidazole), and [(H₂L4)(ZnCl₄)]·H₂O (6) (L4 = 3,6-bis(imidazol-1-yl)pyridazine)), derived from bis(benzimidazole)/bis(imidazole) and metal(II) chloride dihydrate (zinc(II) chloride and copper(II) chloride dihydrate) were prepared and characterized by IR, X-ray structure analysis, elemental analysis, and TG analysis. The aromatic rings of the cations in all of the compounds are planar. X-ray diffraction analysis revealed that all the complexes have 3-D layer network structures built from hydrogen bonds between the cations and chlorometallate anions. Water molecules also play an important role in structure extension in 2, 5, and 6. The arrangements of the anions and cations in their solid state are dominated not only by size and symmetry of the cations, but also by the non-covalent interactions existing in the crystal structures.     

Coordination studies of 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine towards Cu cation. X-ray studies,spectroscopic characterization and DFT calculations

The reactions of 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine with CuCl₂ · 2H₂O, Cu(NO₃)₂ · 3H₂O and CuSO₄ · 5H₂O have been examined, and four [CuCl₂(dppt)] (1), [CuCl₂(dppt)₂] · 2MeOH (2), [Cu(dppt)₂(H₂O)₂](NO₃)₂ (3) and [Cu(SO₄)(dppt)(H₂O)]_n · nH₂O (4) complexes have been obtained. All the complexes have been structurally and spectroscopically characterized, and compound 4 has been additionally studied by magnetic measurements. The electronic structure of 1 has been calculated with the density functional theory (DFT) method, and the time-dependent DFT calculations have been employed to calculate the electronic spectrum of 1.     

Synthesis,characterization, and antibacterial activities of two new copper(II) glycinate complexes incorporating 2-(4′-thiazolyl)benzimidazole/2-(2-pyridyl)benzimidazole

Two new complexes, [Cu(TBZ)(Gly)(H₂O)]Cl (1) and [Cu(HPB)(Gly)Cl]?·?2H₂O (2) (TBZ?=?2-(4′-thiazolyl)benzimidazole, HPB?=?2-(2-pyridyl)benzimidazole, and Gly?=?glycinate), have been synthesized and characterized by elemental analysis, molar conductivity, UV-Vis, and IR methods. The complexes, structurally characterized by single-crystal X-ray crystallography, show a slightly distorted square-pyramidal coordination geometry in which two nitrogen atoms of TBZ or HPB and the carboxylate oxygen and amino nitrogen of glycinate bind in the plane and a water or chloride coordinated at the axial site. The complexes, free ligands, and copper(II) chloride were tested for their ability to inhibit growth of Bacillus subtilis, Staphylococcus aureus, and Salmonella. The results show that the complexes have good antibacterial activities against the microorganisms compared with their ligands and copper(II) chloride.     

Substitution behavior of square-planar and square-pyramidal Cu(II) complexes with bio-relevant nucleophiles

Substitution reactions of [CuCl₂(en)] and [CuCl₂(terpy)] complexes (where en = 1,2-diaminoethane and terpy = 2,2′:6′,2″-terpyridine) with bio-relevant nucleophiles such as inosine-5′-monophosphate (5′-IMP), guanosine-5′-monophosphate (5′-GMP), L-methionine (L-Met), glutathione (GSH) and DL-aspartic acid (DL-Asp) have been investigated at pH 7.4 in the presence of 0.010 M NaCl. Mechanism of substitution was probed via mole-ratio, kinetic, mass spectroscopic and EPR studies at pH 7.4. In the presence of an excess of chloride, the octahedral complex anion [CuCl₄(en)]^2? is formed rapidly while equilibrium reaction was observed for [CuCl₂(terpy)]. Different order of reactivity of bio-molecules toward Cu(II) complexes was observed. Mass spectrum of [CuCl₂(terpy)] in Hepes buffer has shown two new signals at m/z = 477.150 and m/z = 521.00, assigned to [CuCl(terpy)]⁺-Hepes fragments of coordinated Hepes buffer. These signals also appear in the mass spectra of ligand substitution reactions between [CuCl₂(terpy)] and bio-molecules in molar ratio 1:1 and 1:2. According to EPR data, L-Met forms the most stable complex with [CuCl₂(en)] among the ligands considered, while [CuCl₂(terpy)] complex did not show significant changes in its square-pyramidal geometry in the presence of the buffer or bio-ligands.     

EPR study on the charge-transfer photochemistry of the bromide mixed-ligand dithiocarbamate complex of copper(II)

The EPR technique has been used to study the photolysis of the mixed-ligand complex Cu^II(Et₂dtc)Br in a 1:1 solvent mixture of chloroalkane and alcohol, where the chloroalkane is CCl₄, CHCl₃ or CH₂Cl₂ and the alcohol is MeOH, EtOH, i-PrOH or i-BuOH, in comparison with Cu^II(Et₂dtc)Cl photolysis in CHBr₃:ROH. It was found that while Cu^II(Et₂dtc)Br photolysis in chloroalkane:ROH yielded Cu^II(Et₂dtc)Cl as an intermediate, the opposite conversion of Cu^II(Et₂dtc)Cl to Cu^II(Et₂dtc)Br proceeded via Cu^II(Et₂dtc)Cl photolysis in CHBr₃:ROH. The final photolytic products in both cases were tetraethylthiuramdisulphide and the corresponding copper(II) salt (CuCl₂ or CuBr₂, respectively). The results obtained by EPR allowed to get some insight into the behaviour of the primary photolytic products towards both components of the mixed solvent.     

Synthesis and structural characterization of two bond isomer copper(II) complexes via molecular modeling coupled with X-ray powder diffractometry

The reaction of the ambidentate ligand 2-(3,4-dichlorophenyl)imino-N-(2-thiazin-2-yl)thiazolidine (TdTz) with CuCl₂·2H₂O results in the formation of two new copper complexes, which has been characterized in the solid state by elemental analysis, UV-Vis-NIR diffuse reflectance, electron paramagnetic resonance (EPR) spectroscopy, magnetic measurements, infrared spectroscopy and X-ray powder diffraction. These studies have revealed that the two copper complexes are linkage isomers, which the metal atom is four-coordinated by two chloride ions and one ligand TdTz that act as a N,N bidentate ligand in one case and as a N,S bidentate ligand in the other one.     

Synthesis,crystal structure and Raman spectra of [dabcoH2]CuICl3, [dabcoH2]3Cl4CuIICl4(DMSO) and Cu3Cl3(dabco)(DMSO) (dabco = 1,4-diazabicyclo [2.2.2] octane)

Dissolving elemental copper in a CCl₄–DMSO mixture in the presence of dabco (dabco = 1,4-diazabicyclo [2.2.2] octane) resulted in the formation of a compound with the composition [dabcoH₂][CuCl₃] featuring a univalent copper salt. This compound, composed of discrete dabcoH₂²⁺ cations and CuCl₃^2? anions, represents the first example of a copper(I) chloride derivative containing a doubly protonated [dabcoH₂]²⁺ unit, and a very rare example of the oxidative dissolving of copper in a CCl₄–DMSO mixture to give a Cu(I) compound. The addition of some drops of water to the initial reaction mixture led to the formation of the [dabcoH₂]₃Cl₄CuCl₄(DMSO). Three [dabcoH₂]²⁺ units and four Cl^? anions, bound via N–H…Cl hydrogen bonds, form a horseshoe-like cationic fragment. The divalent copper ion possesses a rather unusual pseudo-tetrahedral surrounding. The comproportionation reaction of CuCl₂·2H₂O and copper powder in the presence of dabco in DMSO results in the formation of the Cu₃Cl₃(dabco)(DMSO) complex. Copper and chlorine ions form unprecedented Cu₆Cl₆ cores, interconnected by neutral dabco linkers into infinite 2-D layers. All the compounds were characterized using the single-crystal X-ray diffraction technique and Raman spectroscopy.     

Synthesis of 3-(pyridine-2-yl)-4,5-dihydro-1H-pyrazole-1-thiocarboxamides and their copper(II) complexes

New organic ligands 3-(pyridine-2-yl)-4,5-dihydro-1H-pyrazole-1-thiocarboxamides (L) have been synthesized by a two or three step reaction sequence starting from substituted benzaldehydes and 2-acetyl pyridine. Copper(II) complexes with LCuCl₂ composition were obtained by the reactions of these ligands with CuCl₂·2H₂O. The crystal structure of two synthesized complexes has been determined by X-ray analysis. Copper atoms located in a strongly distorted square piramidal environment and coordinated by pyrazoline and pyridine nitrogen atoms, thiocarbamoyl sulfur atom and two chloride-anions. All complexes undergo reversible or quasi-reversible electrochemical reduction at 0.45–0.28 V with the formation of Cu(I) containing intermediates. The cytotoxicity of copper containing complexes, comparable to cisplatin and doxorubicin, was demonstrated using cancer cell lines MCF-7, A549 and HEK293.     

Reactions of divalent transition metal halides with 3,5-dimethyl-1-(hydroxymethyl)-pyrazole

Factors determining the complex formation reaction of copper(II), nickel(II) and cobalt(II) chloride and copper(II) bromide with 3,5-dimethyl-1-(hydroxymethyl)-pyrazole (HL) has been studied. Depending on experimental conditions, complexes with different composition were obtained: [CuCl₂(dmp)]₂ (I), [CuCl₂(dmp)₂]₂ (II), [CoCl₂(dmp)₂] (III) (dmp=3,5-dimethylpyrazole), [CuBr(L)]₂ (IV), [CoCl(L)(EtOH)]₄ (V) and [NiCl(L)(EtOH)]₄ (VI). The compounds were characterized by FTIR spectroscopy, solution conductivity and magnetic measurements. The crystal structure of [CoCl(L)(EtOH)]₄ has been determined by single crystal X-ray diffraction. The thermal decomposition of the compounds was studied and found to be continuous for all of the compounds. The desolvation mechanism of [MCl(L)(EtOH)]₄ (M=Co(II), Ni(II)) is explained on the basis of the route of complex formation of CoCl₂ with HL.     

Copper(II) Complexes of Spirohydantoins. Synthesis,Quantum-Chemical,and Spectroscopic Study

A series of new Cu(II) complexes with important physiologically active cycloalkane-5-spirohydantoines are synthesized reacting as a result of CuCl₂ · 2H₂O interaction with the ligands in alkaline water medium. Their structures were studied using spectroscopic (IR and EPR) methods. For comparison, ab initio calculations of the structure and IR spectra of the corresponding Cu(II) complexes were also performed. It was proven that with cyclopentane-5-spirohydantoins, distorted (flattened) tetrahedral structure is realized Cu(L_–H)₂(H₂O)₂, while with the higher cycloalkane-5-spirohydantoins linear Cu(II) complexes of the type CuL_–H(OH) are formed.     

Oxido-pincer complexes of copper(II) - An EXAFS and EPR study of mono- and binuclear [(pydotH2)CuCl2]n (n = 1 or 2)

The oxido-pincer ligand pydotH₂ (2,6-bis(1-hydroxy-1-o-tolyl-ethyl-η²O,O′)pyridine) forms two different Cu^II containing complexes when prepared from anhydrous CuCl₂. A combination of EPR spectroscopy and EXAFS allowed to structurally characterise the light-green dimer of the formula [(pydotH₂)CuCl(μ-Cl)₂ClCu(pydotH₂)] and the penta-coordinate olive-green monomer [(pydotH₂)CuCl₂]. The molecular entities imply that the ligand remains protonated upon coordination. When dissolved in DMF both compounds form monomeric species [(pydotH₂)CuCl₂(DMF)] which could be characterised in detail by EPR, UV-Vis/NIR spectroscopy and electrochemical measurements. The assignments were supported by comparison with Cu^II complexes of the related ligands 2,6-bis(hydroxymethyl)pyridine (pydimH₂) and 2,6-bis(1-hydroxy-1-methyl)pyridine (pydipH₂).     

Synthesis and crystal structure of Cu(I) and Ni(II) complexes of 1,1-diethyl-3-(4-fluorobenzoyl)-thiourea

The reaction of 1,1-diethyl-3-(4-fluorobenzoyl)-thiourea (HL) with CuCl₂ ·?2H₂O and NiCl₂ ·?6H₂O give two complexes, Cu(HL)₃Cl (1) and NiL₂ (2). The crystal structures of these products were determined by single crystal X-ray diffraction. In 1, three HL molecules are unidentate, coordinating through the sulfur, and the copper is tetrahedral with three S and one Cl. In 2, two HL molecules are O and S donor bidentate and coordinate as anionic species with loss of the proton from the acyl-substituted nitrogen; the nickel is square-planar.     

An efficient stereoselective synthesis of (E)- and (Z)-trisubstituted alkenes from unactivated Baylis-Hillman adducts using NaBH4/CuCl2·2H2O

A convenient and facile stereoselective synthesis of (E)- and (Z)-trisubstituted alkenes has been achieved by treatment of unactivated Baylis-Hillman adducts with NaBH₄ in the presence of CuCl₂·2H₂O at room temperature for 15 min.