Adjacent Copper Atoms Research Articles

Chlorine bridge bond-enabled binuclear copper complex for electrocatalyzing lithium–sulfur reactions

Engineering atom-scale sites are crucial to the mitigation of polysulfide shuttle, promotion of sulfur redox, and regulation of lithium deposition in lithium–sulfur batteries. Herein, a homonuclear copper dual-atom catalyst with a proximal distance of 3.5 Å is developed for lithium–sulfur batteries, wherein two adjacent copper atoms are linked by a pair of symmetrical chlorine bridge bonds. Benefiting from the proximal copper atoms and their unique coordination, the copper dual-atom catalyst with the increased active interface concentration synchronously guide the evolutions of sulfur and lithium species. Such a delicate design breaks through the activity limitation of mononuclear metal center and represents a catalyst concept for lithium–sulfur battery realm. Therefore, a remarkable areal capacity of 7.8 mA h cm−2 is achieved under the scenario of sulfur content of 60 wt.%, mass loading of 7.7 mg cm−2 and electrolyte dosage of 4.8 μL mg−1.

A Site Distance Effect Induced by Reactant Molecule Matchup in Single-Atom Catalysts for Fenton-Like Reactions.

Understanding the site interaction nature of single-atom catalysts (SACs), especially densely populated SACs, is vital for their application to various catalytic reactions. Herein, we report a site distance effect, which emphasizes how well the distance of the adjacent copper atoms (denoted as dCu1-Cu1 ) matches with the reactant peroxydisulfate (PDS) molecular size to determine the Fenton-like reaction reactivity on the carbon-supported SACs. The optimized dCu1-Cu1 in the range of 5-6 Å, which matches the molecular size of PDS, endows the catalyst with a nearly two times higher turnover frequency than that of dCu1-Cu1 beyond this range, accordingly achieving record-breaking kinetics for the oxidation of emerging organic contaminants. Further studies suggest that this site distance effect originates from the alteration of PDS adsorption to a dual-site structure on Cu1 -Cu1 sites when dCu1-Cu1 falls within 5-6 Å, significantly enhancing the interfacial charge transfer and consequently resulting in the most efficient catalyst for PDS activation so far.

A Site Distance Effect Induced by Reactant Molecule Matchup in Single‐Atom Catalysts for Fenton‐Like Reactions

AbstractUnderstanding the site interaction nature of single‐atom catalysts (SACs), especially densely populated SACs, is vital for their application to various catalytic reactions. Herein, we report a site distance effect, which emphasizes how well the distance of the adjacent copper atoms (denoted as dCu1−Cu1) matches with the reactant peroxydisulfate (PDS) molecular size to determine the Fenton‐like reaction reactivity on the carbon‐supported SACs. The optimized dCu1−Cu1 in the range of 5–6 Å, which matches the molecular size of PDS, endows the catalyst with a nearly two times higher turnover frequency than that of dCu1−Cu1 beyond this range, accordingly achieving record‐breaking kinetics for the oxidation of emerging organic contaminants. Further studies suggest that this site distance effect originates from the alteration of PDS adsorption to a dual‐site structure on Cu1−Cu1 sites when dCu1−Cu1 falls within 5–6 Å, significantly enhancing the interfacial charge transfer and consequently resulting in the most efficient catalyst for PDS activation so far.

A nitrate bridged one-dimensional copper(II) coordination polymer with a tridentate (NNO) Schiff base: synthesis, X-ray structure and catalytic efficacy

A one-dimensional Cu(II) coordination polymer of [Cu(L)(μ-ONO2)]n (1) (HL = 4-methoxy-2-[1-(methylaminoethylimino)methyl]-phenol) with bidentate bridging nitrate has been isolated and characterized by X-ray diffraction analysis and spectroscopic studies. Single crystal X-ray analysis revealed that each copper(II) center in the asymmetric unit of complex 1 adopts a distorted square pyramidal geometry with a CuN2O3 chromophore ligated through a tridentate Schiff base (L) with (NNO) donor sets and two O atoms of bridging nitrate ion. The adjacent copper atoms are connected by bridging nitrate (μ-ONO2) in bidentate fashion affording a 1D coordination polymeric chain structure along the crystallographic b-axis. In the polymeric framework, the Cu…Cu separation is 4.3749(4) A. The catalytic efficacy of complex 1 was studied in a series of solvents for the epoxidation of cyclooctene using tert-butyl-hydroperoxide (TBHP) as an efficient oxidant under mild conditions. The catalytic reaction mixture was analyzed by gas chromatography and the data indicated that the yield of the epoxidation reaction and its selectivity is maximum in acetonitrile medium.

Syntheses, structures and magnetic behaviors of 1D and 3D µ1,5-dicyanamide bridged copper(II) coordination polymers containing a symmetrical 1,2-diamine as a chelator

Two neutral copper(II) coordination polymers, [Cu(en)(µ1,5-dca)(dca)]n (1) and [Cu3(en)2(µ1,5-dca)6]n (2) [en = 1,2-ethanediamine, dca = dicyanamide], with µ1,5-dicyanamide bridges have been isolated. X-ray structural analysis reveals that each Cu(II) center in the asymmetric unit of 1 adopts a distorted square pyramidal geometry with a CuN5 chromophore ligated through two N atoms of the symmetrical 1,2-ethanediamine (en) ligand, one nitrile N atom of a terminal dca ligand and two nitrile N atoms of the μ1,5 bridging dca ligand. 1 is an example of coordination polymer containing both μ1,5-dca and terminal dca. Adjacent copper atoms are connected by dca ligands in the μ1,5-bridging mode affording a 1D chain structure. In the crystalline state, these 1D chains are further associated through weak intermolecular NH⋯N hydrogen bonds to form a 2D sheet structure, viewed along the crystallographic b axis. The asymmetric unit of 2 contains two types of copper(II) centers (Cu1 and Cu2). Cu1 adopts a distorted square pyramidal geometry with a CuN5 chromophore coordinated through two N atoms of the bidentate ligand (en) and three nitrile N atoms of three different μ1,5 bridged dca ligands, whereas Cu2 is connected to six nitrile atoms of six different μ1,5 bridged dca ligands, resulting in a distorted octahedral geometry with a CuN6 chromophore. Adjacent copper atoms are connected by μ1,5-bridging dca ligands to form a 3D network coordination polymer structure, which contains multiple NH∙∙∙N hydrogen bonds in the crystalline state. A variable-temperature magnetic susceptibility study shows very weak antiferromagnetic interactions among the neighboring metal centers through the μ1,5-dca bridges with J = −0.12 cm−1 for complex 1 and J = −0.19 cm−1 for complex 2.

Copper atom-pair catalyst anchored on alloy nanowires for selective and efficient electrochemical reduction of CO2.

The electrochemical reduction of CO2 could play an important role in addressing climate-change issues and global energy demands as part of a carbon-neutral energy cycle. Single-atom catalysts can display outstanding electrocatalytic performance; however, given their single-site nature they are usually only amenable to reactions that involve single molecules. For processes that involve multiple molecules, improved catalytic properties could be achieved through the development of atomically dispersed catalysts with higher complexities. Here we report a catalyst that features two adjacent copper atoms, which we call an 'atom-pair catalyst', that work together to carry out the critical bimolecular step in CO2 reduction. The atom-pair catalyst features stable Cu10-Cu1x+ pair structures, with Cu1x+ adsorbing H2O and the neighbouring Cu10 adsorbing CO2, which thereby promotes CO2 activation. This results in a Faradaic efficiency for CO generation above 92%, with the competing hydrogen evolution reaction almost completely suppressed. Experimental characterization and density functional theory revealed that the adsorption configuration reduces the activation energy, which generates high selectivity, activity and stability under relatively low potentials.

Copper atomic contacts exposed to water molecules.

Monatomic and molecular hydrogen and also oxygen, as well as water molecules and OH that are exposed to atomic copper in intimate contact, have been studied theoretically using computational methods. The authors optimized moderately large structures of Cu/H/Cu, Cu/HCuH/Cu, Cu/H2/Cu, Cu/H2O/Cu, Cu/OH/Cu, Cu/O/Cu, and Cu/O2/Cu and calculated appropriate values for conductance and inelastic tunneling spectroscopy (IETS) properties of the contact junctions, elucidating them as being a possible outcome resulting from the exposure of copper electrodes to the atomic/molecular contaminant species. Here we also demonstrate the IETS properties, by means of ab initio calculations, which can determine the form of the junction geometries. Furthermore, we identify the bonding geometries at the interfaces of the copper electrodes that directly give rise to the specific IETS signatures that have been observed in recent experiments. Based on low-bias conductance and IETS calculations, for the specific case of water exposure of copper electrodes, it was concluded that a single hydrogen or a single oxygen atom bridging the copper electrodes is not responsible for the high conductance peak measurements. Regarding Model 4, where an individual water molecule is considered to be the bridging constituent, our computational results suggest that it has a relatively low probability of being an appropriate candidate. Based upon current computational results, the two hydrogens in Model 3 appear to be in molecular form, although they still form a bond with the adjacent copper atoms. Comparing computational with experimental results indicates that Model 3 is in acceptable agreement with available data.

Novel copper(II) coordination polymer containing the drugs nalidixic acid and 8-hydroxyquinoline: Evaluation of the structural, magnetic, electronic, and antitumor properties

Herein we describe the synthesis, structural characterization, physical/spectroscopic studies and evaluation of the antitumoral activity of a new copper(II) coordination polymer, [Cu(ndx)(8-hq)]n, where H(ndx) is nalidixic acid and H(8-hq) is 8-hydroxyquinoline. Single crystal X-ray diffraction shows a zigzag polymeric chain, where the adjacent copper atoms are connected via anti-anti μ-carboxylate bridge of ndx. This structural feature is quite different from those previously proposed for quinolone complexes. Variable-temperature magnetic susceptibility measurements showed weak antiferromagnetic interactions between the paramagnetic copper centers (−0.49 cm−1). In solution, the compound exists as neutral mononuclear species and it can inhibit the growth of a human chronic myelogenous leukemia cell line (K562) in a concentration-dependent manner with IC50 value lower than those of the corresponding free ligands. At similar doses, the compound does not alter the viability of human keratinocytes (HaCaT cell line). Spectroscopic data and viscosity measurements show that the compound binds to DNA (Kb = 2.47 × 105 M−1) interacting with it by a non-intercalative mode.

Structural Diversity due to Amino Alcohol Ligands Leading to Rare μ4-Hydroxo-Bridged Tetranuclear and “Bicapped Cubane” Cores in Copper(II) Complexes: A Theoretical and Experimental Magnetostructural Study

The μ4-hydroxo- and alkoxo-bridged tetranuclear copper(II) complexes, [Cu4(μ4-OH)(dmae)4][Ag(NO3)4] (1), [Cu4(μ4-OH)(dmae)4][Na(NO3)4] (2), [Cu4(μ4-OH)(dmae)4][K(NO3)4] (3), and hexanuclear alkoxo-bridged "bicapped cubane" copper(II) complex [Cu6(ae)8(ClO4)2](ClO4)2·MeOH (8) (dmae = N,N-dimethylaminoethanolato and ae = 2-aminoethanolato) were synthesized via self-assembly from chelating amino alcohols and copper(II), silver (1), sodium (2), and potassium (3) nitrates or copper(II) perchlorate (8). The complexes are characterized by elemental analyses, single-crystal X-ray diffraction, and variable temperature magnetic measurements. The crystal structures of complexes 1-3 consist of almost planar tetranuclear [Cu4(μ4-OH)(dmae)4](3+) units, in which Cu(II) ions are also weakly bonded to nitrate anions. The adjacent tetranuclear units of 1-3 are connected by ionic interactions between nitrate anions and sodium, potassium, or silver cations resulting in the formation of 1D polymers. The crystal structure of 8 consists of hexanuclear [Cu6(ae)8](4+) "bicapped cubane" units, in which the capping Cu(II) ions are weakly bonded to perchlorate anions. The adjacent hexanuclear units of 8 are connected by hydrogen bonds resulting in the formation of 3D hydrogen bonded networks. Also the results from the synthetic studies leading to the formation of new copper(II) and silver(I) complexes (4-7) using Hae, 3-aminopropanol (Hap), and N,N-dimethylaminopropanol (Hdmap) in similar reactions, which gave tetra- and hexanuclear complexes, are presented. Experimental magnetic studies showed that complexes 1 and 2 exhibit dominant antiferromagnetic coupling leading to an S = 0 ground state, whereas 8 exhibits a large dominant antiferromagnetic interaction between the capping copper atoms and the copper atoms of the top and bottom faces of the cubane unit that define two isosceles triangles. This interaction leads to an S = 1/2 ground state for each triangle. The weak ferromagnetic interaction between these doublet states through the cubane unit leads to a triplet S = 1 ground state for 8. The values of the magnetic exchange coupling constant were the following: J = +1.8 (1) and +2.9 cm(-1) (2) between adjacent copper atoms; J' = -29.2 (1) and -32.2 cm(-1) (2) between opposite copper atoms; J = -297.6 cm(-1) and zJ' = +0.07 cm(-1) (8). Magnetic coupling constants calculated for 2 and 8 by DFT methods are in general of the same nature and magnitude as the experimental ones.

Direct Synthesis and Characterization of New Copper(II) and Zinc(II) 5‐R‐Tetrazolato Complexes [R = Me, Ph, 4‐Py] with Ethylenediamine and DMSO as Coligands

AbstractThree novel 5‐R‐tetrazolato complexes (R = Me, Ph, 4‐Py), namely [Zn2(MeCN4)4(DMSO)2] (1), [Cu2(PhCN4)4(en)2]·2DMSO (2), and [Cu(4‐PyCN4)2(DMSO)2]·4DMSO (3), were isolated as unexpected products under attempts to prepare heterometallic tetrazolates using a direct synthesis strategy in the Cu0‐ZnO‐en‐RCN4H‐DMSO system (en = ethylenediamine). The prepared compounds were characterized by elemental, single‐crystal X‐ray, and thermal analyses, and IR spectroscopy. Variation of the 5‐substituent of the tetrazole ring causes different composition of complexes 1–3 and diverse coordination modes of 5‐R‐tetrazolato ligands. Complex 1 is a 3D coordination polymer due to N1, N4‐bridging of 5‐methyltetrazolato anions. Complex 2, with en as a coligand, has a dinuclear structure with two copper atoms linked together by two 5‐phenyltetrazolato ligands by tetrazole N2, N3 bridges. Complex 3 represents a 2D coordination polymer, formed due to 5‐(4‐pyridyl)tetrazolato bridges between adjacent copper atoms (with the tetrazole and pyridine rings nitrogen atoms as coordination centers). DMSO molecules, included in all the compounds, are solvate and/or coordinated ones.

A new 1D chiral metal-organic coordination polymer constructed by Cu(II) with L-3-Cyanophenylalanine

A new 1D chiral metal-organic coordination polymer [Cu(Cphe)2] · 3H2O (I) (HCphe = L-3-Cyanophenylalanine) has been synthesized in an aqueous solution and characterized by elemental analysis, thermogravimetric analysis (TGA), X-ray powder diffraction (XRPD), infrared spectroscopy (IR) and single crystal X-ray diffraction. The X-ray diffraction analysis reveals that I crystallizes in the monoclinic space group P21. The adjacent copper(II) atoms are linked by Cphe ligands to form a 1D zigzag chain, which is further connected via strong hydrogen bonds to form a 3D supramolecular framework. The unit cell parameters for I are: a = 12.0201(8), b = 6.1495(4), c = 14.8576(10) A, β = 94.1720(10)°, V = 1095.00(13) A3, and Z = 2.

Synthesis, crystal structure, and characterizations of a 3-D Cu(I) complex with 1,6-bi(benzotriazole)hexane

Solvothermal reaction of the flexible ligand 1,6-bi(benzotriazole)hexane (BBTH) with CuCl generated a 3-D hybrid solid, {[CuCl]2(BBTH)} n (1), which was investigated by elemental analysis, FT-IR, X-ray powder diffraction (XRPD), X-ray single-crystal diffraction, TG/DTA, and photoluminescence measurements. Compound 1 crystallizes in the tetragonal system, space group I4(1)/a, a = b = 17.636(2) Å, c = 13.5345(15) Å, V = 4209.6(9) Å3, Z = 8. The distorted tetrahedral geometry of Cu(I) is defined by two chlorides and two N donors from different BBTH ligands. Adjacent copper atoms are connected by μ2-Cl to give a 1-D zigzag inorganic chain, and further linked by BBTH ligands via μ4-bridging, forming the 3-D hybrid structure of 1. Cu(I) atoms and BBTH ligands can be regarded as two kinds of non-equivalent 4-connected nodes, which lead to an unusual topological network with Schläfli symbol of (32.8.92.10)2(32.82.92). Compound 1 exhibits high thermal stability and shows strong red fluorescence emission at 538 nm in the solid state at ambient temperature.

Structure and magnetic property of μ-alkoxo–μ-6-methoxypurinate double bridged dinuclear copper(II) complex

A new μ-alkoxo–μ-6-methoxypurinate double bridged dinuclear copper(II) complex [Cu 2(L)(μ-6-meo-pur)(dmf)] ( 1) (μ-6-meo-pur = μ-6-methoxypurinate, H 3L = 1,3-bis(3,5- tert-butyl-salicylideneamino)-2-propanol; dmf = N,N-dimethylformamide) has been prepared and structurally characterized. The single crystal X-ray analysis show that the structure of complexes 1 is dimeric with two adjacent copper(II) atoms double bridged by μ-alkoxo–μ-purinato with the Cu···Cu distances and Cu–O(alkoxo)–Cu angles 3.227(3) Å and 110.30(11)°, respectively. Magnetic measurements reveal that 1 is a ferromagnetically coupled with exchange parameter of 2 J = 56.2 cm −1. DFT calculation of spin density of HOMO for 1 was presented.

Crystal Structures, Magnetic Properties and Catecholase‐Like Activities of μ‐Alkoxo‐μ‐Carboxylato Double Bridged Dinuclear and Tetranuclear Copper(II) Complexes

AbstractOne μ‐alkoxo‐μ‐carboxylato bridged dinuclear copper(II) complex, [Cu2(L1)(μ‐C6H5CO2)] (1)(H3L1 = 1,3‐bis(salicylideneamino)‐2‐propanol)), and two μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear copper(II) complexes, [Cu4(L1)2(μ‐C8H10O4)(DMF)2]·H2O (2) and [Cu4(L2)2(μ‐C5H6O4]·2H2O·2CH3CN (3) (H3L2 = 1,3‐bis(5‐bromo‐salicylideneamino)‐2‐propanol)) have been prepared and characterized. The single crystal X‐ray analysis shows that the structure of complex 1 is dimeric with two adjacent copper(II) atoms bridged by μ‐alkoxo‐μ‐carboxylato ligands where the Cu···Cu distances and Cu‐O(alkoxo)‐Cu angles are 3.5 11 Å and 132.8°, respectively. Complexes 2 and 3 consist of a μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear Cu(II) complex with mean Cu‐Cu distances and Cu‐O‐Cu angles of 3.092 Å and 104.2° for 2 and 3.486 Å and 129.9° for 3, respectively. Magnetic measurements reveal that 1 is strong antiferromagnetically coupled with 2J =‐210 cm−1 while 2 and 3 exhibit ferromagnetic coupling with 2J = 126 cm−1 and 82 cm−1 (averaged), respectively. The 2J values of 1–3 are correlated to dihedral angles and the Cu‐O‐Cu angles. Dependence of the pH at 25 °C on the reaction rate of oxidation of 3,5‐di‐tert‐butylcatechol (3,5‐DTBC) to the corresponding quinone (3,5‐DTBQ) catalyzed by 1–3 was studied. Complexes 1–3 exhibit catecholase‐like active at above pH 8 and 25 °C for oxidation of 3,5‐di‐tert‐butylcatechol.

Syntheses, structures and magnetic properties of two copper(II) tricyanomethanide complexes with 2,2′-bipyrimidine as bridging ligands

Two copper(II) tricyanomethanide (tcm) complexes with 2,2′-bipyrimidine (bpym) as co-ligands Cu 4(bpym) 5(tcm) 8 · 2H 2O ( 1) and [Cu 2(bpym) 2(tcm) 4 · H 2O] n ( 2) have been synthesized, and structurally and magnetically characterized. Compound 1 displays a tetranuclear structure, in which each middle copper(II) atom is coordinated by two bridging bpym molecules and two terminal tcm ligands to form a tetragonal bipyramidal geometry, while each side copper(II) atom is surrounded by one bridging bpym, one terminal bpym, one terminal bonded tcm and one terminal weakly coordinated tcm ligands to give a square bipyramidal geometry. In 1 the four neighbouring copper(II) atoms are joined to each other by the bpym molecules, which leads to the formation of a tetranuclear structure. Compound 2 features an infinite chain structure, in which two slightly different chains exist. In each chain the copper(II) atom is bonded to two bridging bpym molecules and two terminal tcm ligands to form a tetragonal bipyramidal geometry, the adjacent copper(II) atoms are linked each other by the bpym ligands to define an infinite chain structure. In 2 the distances between two neighbouring copper(II) atoms in one chain are different. Moreover these distances in one chain are also different from those of the other chain. Magnetic susceptibility measurements for the two complexes in the temperature range 2–300 K reveal the occurrence of significant antiferromagnetic interactions for 1 ( J 1 = −20.42 cm −1, J 2 = −5.29 cm −1 and g = 2.22) and 2 ( T > 50 K, θ = −20.00 K, C = 0.86 cm 3 mol −1 K), respectively.

Synthesis, structure, and magnetic properties of two 1-D helical coordination polymeric Cu(II) complexes

Two helical coordination polymeric copper(II) complexes bearing amino acid Schiff bases HL or HL′, which are condensed from 2-hydroxy-1-naphthaldehyde with 2-aminobenzoic acid or l-valine, respectively, have been prepared and characterised by X-ray crystallography. In [CuL] n ( 1) the copper(II) atoms are bridged by syn– anti carboxylate groups giving infinite 1-D right-handed helical chains which are further connected by weak C–H⋯Cu interactions to build a 2-D network. While in [CuL′] n ( 2) the carboxylate group acts as a rare monatomic bridge to connect the adjacent copper(II) atoms leading to the formation of a left-handed helical chain. Magnetic susceptibility measurements indicate that 1 exhibits weak ferromagnetic interactions whereas an antiferromagnetic coupling is established for 2. The magnetic behavior can be satisfactorily explained on the basis of the structural data.

Magnetostructural correlations and catecholase-like activities of μ-alkoxo-μ-carboxylato double bridged dinuclear and tetranuclear copper(II) complexes

Two μ-alkoxo-μ-carboxylato bridged dinuclear copper(II) complexes, [Cu 2(L 1)(μ-HCO 2)] ( 1) ((H 3L 1 = 1,3-bis(5-bromosalicylideneamino)-2-propanol)), [Cu 2(L 2)(μ-HCO 2)] · dmf ( 2) (H 3L 2 = 1,3-bis(3,5-chlorosalicylideneamino-2-propanol)), and two μ-alkoxo-μ-dicarboxylato doubly bridged tetranuclear copper(II) complexes, [{Cu 2(L 3)} 2(μ-O 2C–C(CH 3) 2–CO 2)] · 5H 2O · 3CH 3OH ( 3) ((H 3L 3 = 1,3-bis(salicylid-deneamino)-2-propanol)) and [{Cu 2(L 3)} 2(μ- O 2CCH 2–C 6H 4–CH 2CO 2)] · 2H 2O ( 4) have been prepared and characterized. The single crystal X-ray analysis shows that the structures of complexes 1 and 2 are dimeric with two adjacent copper(II) atoms bridged by μ-alkoxo-μ-carboxylato ligands with the Cu⋯Cu distances and Cu–O(alkoxo)–Cu angles are 3.511 Å and 132.85° for 1, 3.517 Å and 131.7° for 2, respectively. Complexes 3 and 4 consist of μ-alkoxo-μ-dicarboxylato doubly bridged tetranuclear Cu(II) complexes with mean Cu–Cu distances and Cu–O–Cu angles of 3.158 Å and 108.05° for 3 and 3.081 Å and 104.76° for 4, respectively. Magnetic measurements reveal that 1 and 2 are strong antiferromagnetically coupled with 2 J = −156 and −152 cm −1, respectively, while 3 and 4 exhibit ferromagnetic coupling with 2 J = 86 and 155.2 cm −1, respectively. The 2 J values of 1– 4 are linearly correlated to the Cu–O–Cu angles. Dependence of the pH at 25 °C on the reaction rate of oxidation of 3,4-di- tert-butylcatechol (3,5-dtbc) to the corresponding quinone catalyzed by 1– 4 was studied. Complexes 1– 4 exhibit high catecholase-like activity at pH 9.0 and 25 °C for oxidation of 3,5-di- tert-butylcatechol.

Structures and magnetic properties of one-dimensional polymers constructed with copper(II) salts and pyridinecarboxamide-type ligands

Three complexes of the composition {[Cu(μ 1,5-dca) 2(mppca) 2] · H 2O} n ( 1), [Cu(μ 1,5-dca) 2(nppca) 2] n ( 2) and [Cu(μ-Cl) 2(mppca) 2] n ( 3) (dca = dicyanamide, N ( CN ) 2 - ; mppca = N-(4′-methylphenyl)-4-pyridinecarboxamide; nppca = N-(4′-nitrophenyl)-4-pyridinecarboxamide) have been synthesized and characterized by single crystal X-ray crystallography and magnetic susceptibility studies. Different supramolecular structures of the complexes have been constructed by different non-covalent motifs in the crystalline solids. In complex 1, adjacent copper(II) atoms are connected by double μ 1,5-dca(end-to-end) bridges to form a chain-like structure. The chains are linked by π–π interactions and hydrogen bonds between the ligands and water molecules to form a 3D network. In complex 2, copper(II) atom has a coordination environment similar to 1, but water molecules have not been found. Weak C–H⋯N hydrogen bonding and π–π interaction yield a 3D supramolecular network which is different from that of complex 1. Complex 3 is a 1D polymeric chain in which Cu(II) ions are bridged by Cl −, and only CH/π interactions had been found. Magnetic measurements revealed antiferromagnetic properties of 1, 3 and ferromagnetic behavior of 2.

Synthesis, Characterization, and Olefin/CO Exchange Reactions of Copper(I) Derivatives Containing Bidentate Oxygen Ligands

New hexafluoroacetylacetonate (hfacac) and trifluoroacetato olefin complexes of copper(I) of the general formulas Cu(hfacac)(olefin) and Cu(CF3COO)(olefin) have been prepared from Cu2O/hfacacH/olefin or Cu(CF3COO)(toluene)0.5/olefin systems. The structures of [Cu(hfacac)(coe)], [Cu(hfacac)(van)], [Cu(μ-CF3COO)(tbve)]n, and [Cu(μ-CF3COO)(van)]2·C7H8 have been determined by X-ray diffraction methods, where coe = cyclooctene, van = 4-vinylanisole, and tbve = tert-butyl vinyl ether. In the solid state, the 4-vinylanisole/trifluoroacetate complex [Cu(CF3COO)(van)]2 is dimeric with two carboxylato groups symmetrically bridging two copper atoms, while the tert-butyl vinyl ether derivative [Cu(μ-CF3COO)(tbve)]n is polymeric with single [CF3COO]- bridges between adjacent copper atoms. Olefin hfacac complexes are monomeric, and considering the two oxygen atoms and the midpoint of the double bond of the coordinated olefin, the copper atom lies in a nearly trigonal-planar environment. The carbonylation reactions of C...

A New Cu(II) Bridging-carboxylate Helical Chain Polymer: Synthesis and Structural Aspects

The crystal structure of a new Cu(II) carboxylato-bridged complex [Cu(L)(SCN)]n (1) [where HL = 2-N-(2′-pyridylimine)benzoic acid] forms a helical chain polymer chain. In 1, adjacent copper atoms are linked by carboxylate groups in a syn–anti conformation. The title complex was also characterised by elemental analysis, IR spectra, electronic spectra and variable temperature magnetic measurements.