Kinetics and Mechanism of Acetylene Reduction with Europium Amalgam Catalyzed by Isolated Active Center of Nitrogenase

The reaction kinetics of C₂H₂ reduction with europium amalgam (Eu/Hg) catalyzed by nitrogenase active center separated from the enzyme, the molybdenum–iron–sulfur cluster [MoFe₇S₉ · homocitrate] (FeMoco), was studied. The dependence of the rates of ethylene and ethane formation on the concentrations of catalyst, substrate, protonating agent, and amalgam was studied. The stereospecificity of the reaction was studied by Fourier transform IR spectroscopy. It was found that the reaction occurred at the amalgam surface via the adsorption of the compound [FeMoco · PhSH]. Upon reduction, this compound can simultaneously coordinate several substrate molecules to activate them for the subsequent reactions. A study of the IR spectra of the gas phase of the reaction demonstrated that cis-1,2-dideuterioethylene is the main product of C₂D₂ reduction. Taking into account this fact and the dependence of the reaction rate on the concentration of a protonating agent, we concluded that substrate molecules bound to the cofactor underwent protonation by intramolecular hydrogen transfer from the iron or sulfur atoms of FeMoco to coordinated C₂H₂.     

Synthesis and characterization of a novel crystalline AlPO4 molecular sieve,CFAP-7

The novel crystalline aluminophosphate CFAP-7, having a characteristic X-ray powder diffraction pattern, has been synthesized hydrothermally in a system consisting of di-n-butylamine-(NH₄)₂O–P₂O₅–Al₂O₃–H₂O at 120 to 140°C, the P₂O₅ and Al₂O₃ sources of which were provided by (NH₄)₃PO₄·3H₂O and Al₂(SO₄)₃ in aqueous solution, respectively. Investigations by DTA, TG, DTG, XRD, and IR indicate transformation of the original product (form A) into more stable crystal forms B and C on heating at about 180°C and 240°C, respectively, while liberating water and amine. Isotherms for the adsorption of water and methanol at 23°C show that both form B and form C are molecular sieves with a window dimension of 4.3–4.9 Å, and a methanol volume adsorbtion greater than that of water.     

One-step synthesis of carbon-supported Pd–Pt alloy electrocatalysts for methanol tolerant oxygen reduction

A facile, one-step reduction route was developed to synthesize Pd-rich carbon-supported Pd–Pt alloy electrocatalysts of different Pd/Pt atomic ratios. As-prepared Pd–Pt/C catalysts exhibit a single phase fcc structure and an expansion lattice parameter. Comparison of the oxygen reduction reaction (ORR) on the Pd–Pt/C alloy catalysts indicates that the Pd₃Pt₁/C bimetallic catalyst exhibits the highest ORR activity among all the Pd–Pt alloy catalysts and shows a comparative ORR activity with the commercial Pt/C catalyst. Moreover, all the Pd–Pt alloy catalysts exhibited much higher methanol tolerance during the ORR than the commercial Pt/C catalyst. High methanol tolerance of the Pd–Pt alloy catalysts could be attributed to the weak adsorption of methanol induced by the composition effect, to the presence of Pd atoms and to the formation of Pd-based alloys.     

Cu‐Based Catalyst Resulting from a Cu,Zn,Al Hydrotalcite‐Like Compound: A Microstructural,Thermoanalytical, and In Situ XAS Study

A Cu‐based methanol synthesis catalyst was obtained from a phase pure Cu,Zn,Al hydrotalcite‐like precursor, which was prepared by co‐precipitation. This sample was intrinsically more active than a conventionally prepared Cu/ZnO/Al₂O₃ catalyst. Upon thermal decomposition in air, the [(Cu_0.5Zn_0.17Al_0.33)(OH)₂(CO₃)_0.17] ? mH₂O precursor is transferred into a carbonate‐modified, amorphous mixed oxide. The calcined catalyst can be described as well‐dispersed “CuO” within ZnAl₂O₄ still containing stabilizing carbonate with a strong interaction of Cu²⁺ ions with the Zn–Al matrix. The reduction of this material was carefully analyzed by complementary temperature‐programmed reduction (TPR) and near‐edge X‐ray absorption fine structure (NEXAFS) measurements. The results fully describe the reduction mechanism with a kinetic model that can be used to predict the oxidation state of Cu at given reduction conditions. The reaction proceeds in two steps through a kinetically stabilized Cu^I intermediate. With reduction, a nanostructured catalyst evolves with metallic Cu particles dispersed in a ZnAl₂O₄ spinel‐like matrix. Due to the strong interaction of Cu and the oxide matrix, the small Cu particles (7 nm) of this catalyst are partially embedded leading to lower absolute activity in comparison with a catalyst comprised of less‐embedded particles. Interestingly, the exposed Cu surface area exhibits a superior intrinsic activity, which is related to a positive effect of the interface contact of Cu and its surroundings.     

Ligand exchange reaction of Zn(II)-acetylacetonate complex with 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid

Ligand exchange reaction of Zn(II)-acetylacetonate complex (Zn-acac₂) with 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid (H₂TPPS) has been investigated spectrophotometrically and radiometrically. The exchange reaction was observed by spectral change from H₂TPPS to Zn-TPPS or activity of⁶⁵Zn(acac)₂ extracted into the chloroform phase. The 2nd order rate constants (k ₂) for the exchange reaction at 70 °C and at pH 7.8 were found to be 32.8±2.3 and 31.2±3.2 M^–1·s^–1 from the spectrometric and radiotracer experiments, respectively. For the direct complexation of Zn(II) with H₂TPPS, a similar 2nd order rate constant (k=32.4±4.7 M^–1·s^–1) was obtained as that in the ligand exchange reaction. The activation energies (E) for the exchange and the formation of Zn-TPPS were found to be 69.3±0.2 and 69.4±0.2 kJ·mol^–1, respectively, in the temperature range from 40 to 70 °C.     

Structural Peculiarities of Water Solutions in <Emphasis Type="Italic">n</Emphasis>-Alkanols Derived from the Study of Bulk Properties at Different Temperatures

The structural behavior of water microimpurities in n-alkanols (C₁-C₇) is considered by using our and literature data on the bulk properties of infinitely dilute solutions of H₂O in the above organic solvents at 278.15 K, 298.15 K, and 318.15 K. Volume effects of water solution in hypothetical alkanols HOH (pseudowater) and H(CH₂)OH (pseudomethanol) with molar volumes corresponding to volume effects in water and methanol in pure liquid states have been evaluated. The behavior of water in methanol, which is distinct from the behavior of other H₂O—n-alkanol systems, is of configurational nature and is associated with the unique molecular structure of this alcohol (i.e., with the absence of hydrocarbon chains in its molecules) and also with steric peculiarities of the arrangement of solute molecules in the structural matrix of the solvent (so-called “edge effect”).Original Russian Text Copyright © 2004 by E. V. Ivanov, V. K. Abrosimov, and E. Yu. Lebedeva__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 862–869, September–October, 2004.     

The ESR Study of O2 – Radical Anion Formation during Adsorption of an NO + O2 Mixture and O2 on ZrO2 and (0.1–2.0)% MoO3/ZrO2

The influence of conditions of the preliminary thermal treatment of ZrO₂, ammonia and methanol adsorption, and MoO₃ supporting on O₂ ^– formation during the adsorption of an NO + O₂ mixture was studied. The interaction of O₂ ^– with different molecules was studied. Adsorbed ammonia and methanol, as well as supported Mo⁶⁺ ions, were shown to inhibit this reaction. The involvement of the Zr⁴⁺ and O^2– Lewis sites in the reaction was concluded. The interaction of ammonia and methanol with the O₂ ^– radical anions changed the g tensor parameters and decreased the thermal stability of O₂ ^– in the case of methanol. O₂ ^– radical anions were formed on the reduced (0.1–2.0)% MoO₃/ZrO₂ samples during the interaction of O₂ with the Mo⁵⁺ ions in the octahedral configuration. As in the case of O₂ ^– formation during NO + O₂ adsorption on ZrO₂, the radical anions were localized in the coordination spheres of the coordinately unsaturated Zr⁴⁺ ions. A change in the MoO₃ content of the samples from 0.1 to 0.5% led to an increase in the amount of O₂ ^–, whereas a change from 0.5 to 2.0% led to a decrease in the O₂ ^– amount due to the screening of the Zr⁴⁺ ions by oxo complexes and polymolybdates.     

Synthesis and Self‐Organization of Zinc β‐(Dialkoxyphosphoryl)porphyrins in the Solid State and in Solution

The first synthesis and self‐organization of zinc β‐phosphorylporphyrins in the solid state and in solution are reported. β‐Dialkoxyphosphoryl‐5,10,15,20‐tetraphenylporphyrins and their Zn^II complexes have been synthesized in good yields by using Pd‐ and Cu‐mediated carbon–phosphorous bond‐forming reactions. The Cu‐mediated reaction allowed to prepare the mono‐β‐(dialkoxyphosphoryl)porphyrins 1 Zn – 3 Zn starting from the β‐bromo‐substituted zinc porphyrinate ZnTPPBr (TPP=tetraphenylporphyrin) and dialkyl phosphites HP(O)(OR)₂ (R=Et, iPr, nBu). The derivatives 1 Zn – 3 Zn were obtained in good yields by using one to three equivalents of CuI. When the reaction was carried out in the presence of catalytic amounts of palladium complexes in toluene, the desired zinc derivative 1 Zn was obtained in up to 72 % yield. The use of a Pd‐catalyzed C? P bond‐forming reaction was further extended to the synthesis of β‐poly(dialkoxyphosphoryl)porphyrins. An unprecedented one‐pot sequence involving consecutive reduction and phosphorylation of H₂TPPBr₄ led to the formation of a mixture of the 2,12‐ and 2,13‐bis(dialkoxy)phosphorylporphyrins 5 H₂ and 6 H₂ in 81 % total yield. According to the X‐ray diffraction studies, 1 Zn and 3 Zn are partially overlapped cofacial dimers formed through the coordination of two Zn centers by two phosphoryl groups belonging to the adjacent molecules. The equilibrium between the monomeric and the dimeric species exists in solutions of 1 Zn and 3 Zn in weakly polar solvents according to spectroscopic data (UV/Vis absorption and NMR spectroscopy). The ratio of each form is dependent on the concentration, temperature, and traces of water or methanol. These features demonstrated that zinc β‐phosphorylporphyrins can be regarded as new model compounds for the weakly coupled chlorophyll pair in the photosynthesis process.     

Understanding the Solvent Effect on the Catalytic Oxidation of 1,4‐Butanediol in Methanol over Au/TiO2 Catalyst: NMR Diffusion and Relaxation Studies

The effect of water on the catalytic oxidation of 1,4‐butanediol in methanol over Au/TiO₂ has been investigated by catalytic reaction studies and NMR diffusion and relaxation studies. The addition of water to the dry catalytic system led to a decrease of both conversion and selectivity towards dimethyl succinate. Pulsed‐field gradient (PFG)‐NMR spectroscopy was used to assess the effect of water addition on the effective self‐diffusivity of the reactant within the catalyst. NMR relaxation studies were also carried out to probe the strength of surface interaction of the reactant in the absence and presence of water. PFG‐NMR studies revealed that the addition of water to the initial system, although increasing the dilution of the system, leads to a significant decrease of effective diffusion rate of the reactant within the catalyst. From T₁ and T₂ relaxation measurements it was possible to infer the strength of surface interaction of the reactant with the catalyst surface. The addition of water was found to inhibit the adsorption of the reactant over the catalyst surface, with the T₁/T₂ ratio of 1,4‐butanediol decreasing significantly when water was added. The results overall suggest that both the decrease of diffusion rate and adsorption strength of the reactant within the catalyst, due to water addition, limits the access of reactant molecules to the catalytic sites, which results in a decrease of reaction rate and conversion.     

Synthesis of heterobimetallic lanthanide <Emphasis Type="Italic">tert</Emphasis>-butoxides and their catalytic properties in reactions of CO<Subscript>2</Subscript> with epoxides

Heterobimetallic tert-butoxides (t-BuO)₅Cu₂Ln (Ln = Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb), (t-BuO)₅MLa (M = Mn, Fe, Co, Ni), (t-BuO)₅ZnNd, and (t-BuO)₄ZnFe were prepared in high yields by the reaction of t-BuOLi with a stoichiometric mixture of a lanthanide halide LnX₃ (Ln = Y, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb; X = Cl, I) and a d-transition metal salt MX_n (M = Zn, Cu, Mn, Fe, Co, Ni; X = Cl, Br). (t-BuO)₅Cu₂Ln (Ln = Y, La, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) and (t-BuO)₅ZnNd at room temperature and atmospheric pressure induce copolymerization of CO₂ with cyclohexene oxide, affording the polycarbonate in a yield of 3–6 g g^–1 catalyst. The complex (t-BuO)₅FeLa, and also iron alcoholates (t-BuO)₂Fe and (t-BuO)2_Fe(bipy) under similar conditions catalyze the reaction of CO₂ with propylene oxide affording monomeric propylene carbonate in a yield of 35–45 g g^–1 catalyst.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1295–1299.Original Russian Text Copyright © 2004 by Nikitinskii, L. Bochkarev, Khorshev, M. Bochkarev.This revised version was published online in April 2005 with a corrected cover date.     

Synthesis,Structure and Properties of Some 3d-Element Complexes with 2-[2-(Hydroxybenzylidene)-amino]-2-hydoxymethylpropane-1,3-diol

2-[2-(Hydroxybenzylidene)-amino]-2-hydoxymethylpropane-1,3-diol (HL) reacts with cobalt, nickel, copper and zinc chlorides, bromides and acetates in water–ethanol solutions and gives MLX · nH₂O and ML₂ · nH₂O complexes (M = Co, Ni, Cu, Zn; X = Cl, Br; n = 0–5). Single crystals of CuLBr were grown, and its crystal structure was determined by X-ray diffraction analysis. The crystals are tetragonal, a = 17.024(2), c = 8.720(2) Å, space group P 2₁ c, Z = 8, R ₁ = 0.0349. In the structure of this complex, the copper atom coordinates the deprotonated HL molecule. The coordination polyhedron of the central atom is an elongated tetragonal pyramid. Its base is built of the imine nitrogen atom, phenolic and alcoholic oxygen atoms, and bromine atom. The apex of the pyramid is occupied by the bromine atom of the adjacent complex connected with the initial complex by the plane of sliding reflection. Thus, the crystal contains infinite chains of complexes running along the c axis, the complexes being united by both bridging bromine atoms and O–H···O hydrogen bonds. The conclusions on the compositions and structures of the remaining compounds were made on the basis of elemental and combined thermal analyses, IR spectroscopy, and magnetic chemistry data. The copper halide complexes were found to have dimeric, and the other metal complexes monomeric, structures. In the synthesized complexes, the azomethine HL can function as a bidentate or tridentate ligand. The thermolysis of the coordination compounds proceeds through the stages of elimination of crystal water molecules (75–90°C) or inner-sphere water molecules (145–155°C) and complete thermal destruction (485–550°C).     

Two-Dimensional Coordination Polymer {[Zn(Pht)(4.4′-Bipy)(H2O)2] · 2H2O} n : Synthesis and Structure

The coordination polymer {[Zn(Pht)(4,4-Bipy)(H₂O)₂] · 2H₂O} _n (where Pht is a doubly deprotonated phthalic acid residue and 4,4-Bipy is 4,4-bipyridine) was synthesized and studied by X-ray diffraction. It was shown that both ligands perform a bridging function and unite the Zn atoms into a two-dimensional network with a periodicity of 11.302(2) Å (with 4,4-Bipy as the bridge) or 7.627(2) Å (with Pht as the bridge). The coordination polyhedron of Zn is a distorted octahedron with C ₂ symmetry. The Zn–N distances in the coordination polyhedron are 2.117(3) and 2.131(3) Å; the Zn–O_carb distance is 2.171(2) Å and the Zn–O(w) distance is 2.129(2) Å. The O–H···O hydrogen bonds involving the outer-sphere water molecules combine the polymer layers into a framework.     

Bis(dimethyldithiocarbamato)(pyridine)zinc and -copper(II) and Their Benzene Solvates: EPR and Solid-State Natural Abundance (13C, 15N) CP/MAS NMR

Adducts of bis(dimethyldithiocarbamato)zinc and -copper(II) complexes with pyridine, [M(Py)(Mdtc)₂], and their benzene solvates [M(Py)(Mdtc)₂] · 0.5C₆H₆ were synthesized. The electron paramagnetic resonance method and solid-state ¹³C and ¹⁵N CP/MAS NMR spectroscopy were used to perform a comparative study of the compounds obtained. The EPR data showed that the geometry of Cu(II) coordination polyhedra both in the adduct itself [Cu(Py)(Mdtc)₂], and in its solvate, [Cu(Py)(Mdtc)₂] · 0.5C₆H₆ is intermediate between a square pyramid (SP) and a trigonal bipyramid (TBP), the contribution from the latter being dominant (75%) in [Cu(Py)(Mdtc)₂]. In the solvated adduct [Cu(Py)(Mdtc)₂] · 0.5C₆H₆, the copper(II) polyhedron is distorted to form an SP-enriched structure (the contribution from TBP is reduced to 55%). It was found NMR data that [Zn(Py)(Mdtc)₂] exists in a single high-symmetry molecular form. Coordinated pyridine molecule shows molecular motion about the Zn–N bond. The solvation of the adduct results in structural nonequivalence of the Mdtc^–ligands in [Zn(Py)(Mdtc)₂] · 0.5C₆H₆. Signals in the ¹⁵N NMR spectra were assigned to the structural positions of the atoms in the previously described molecular structure of a solvated adduct. It was found that the heterogeneous reaction of adduct formation during the absorption of pyridine from the gas phase by polycrystalline [Zn₂(Mdtc)₄] species is accompanied by the dissociation of binuclear molecules.     

Photocatalytic liberation of hydrogen from C1-C4 alcohols with the participation of titanium complexes

It was established that in UV irradiation of solutions of TiCl₄ in methanol, ethanol, isopropanol, and butanol, alcohol-chloride complexes of titanium(III) are formed. The quantum yields of the formation of coordination compounds of titanium(III) depend on the nature of the alcohol: 0.08 (methanol); 0.13 (ethanol); 0.20 (butanol); 0.22 (isopropanol). As complexes of titanium(III) accumulate in solution, there is a liberation of molecular hydrogen. The quantum yields of the formation of hydrogen, determined in a steady-state process, are correlated with the values of the C-H bond energy at the -carbon atom of the alcohol and are equal to 2·10^–3, 3.4·10^–3, 4.3·10^–3 and 1·10^–2 for solutions in methanol, butanol, ethanol, and isopropanol, respectively. A substantial increase in the quantum yield of the formation of molecular hydrogen was detected when a heterogeneous catalyst (palladium on silica gel) was used, and the possible mechanism of the process of photocatalytic liberation of hydrogen from alcohols with the participation of titanium complexes is discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 3, No. 2, pp. 181–186, March–April, 1987.The authors would like to thank V. M. Granchak for his participation in the discussion of the results.     

The structure of water and methanol adsorbed on silica gel by FT-NIR spectroscopy

The NIR adsorption spectra were analyzed quantitatively on the fundamental, combination and first overtone region of OH vibrations of silanol groups, water and methanol adsorbed on mesoporous silica gels. Adsorbed methanol constitutes first layer of about 3 molecules/um^–2 and second layer, the structure of which is similar to that of bulk methanol liquid. Adsorbed water consists of a first layer of about 3 molecules/nm^–2, the second layer of about 9 molecules/nm^–2 and the third layer has a structure similar to the that of bulk water. The molecular configuration at the interface is discussed.     

Synthese von Tetracyanoniccolat-clathraten mit Benzol Kurze Mitteilung

Zusammenfassung Durch Ersetzung des Cadmiums im Clathrat Cden[Ni(CN)₄]·2C₆H₆ wurden drei Verbindungen des TypsM(en) _m[Ni(CN)₄]·nC₆H₆ (M ²⁺=Ni, Cu, Zn;m=2–3;n=0.14–0.28) hergestellt und charakterisiert.

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Synthesis of ethylendiamine-(metal II)-tetracyanoniccolate dibenzene clathrate compounds

Replacing cadmium ion in Cden[Ni(CN)₄]·2C₆H₆ clathrate compound three compounds ofM(en) _m[Ni(CN)₄]·nC₆H₆ type (M ²⁺=Ni, Cu, Zn;m=2–3;n=0.14–0.28) were prepared and characterized.

     

Crystal Structure of Monoprotonated Cobalt(II) Nitrilotriacetate Tetrahydrate Co(HNta) · 4H2O

X-ray diffraction analysis of Co(HNta) · 4H₂O (I) (H₃Nta = N(CH₂COOH)₃) revealed that its crystals are isostructural to a Zn analog and built from [Co(HNta)(H₂O)₃] complex molecules and crystallization water. The octahedral coordination of the Co atom includes two O atoms and an N atom provided by the chelating tridentate HNta^2–ligand (average Co–O (Nta) 2.055 Å and Co–N 2.205 Å) and three O atoms of water molecules on the shared face (average Co–O(w) 2.105 Å).     

Interaction of Phosphorus Iminoilides with Metal Acetates. Crystal and Molecular Structure of Cu[(2-O–)(5-NO2)C6H3N–CH=CH–+PPh3]2 · 2CHCl3

The structure of the Cu[(2-O^–)(5-NO₂)C₆H₃N–CH=CH–⁺PPh₃]₂ complex with the CuN₂O₂ coordination core of distorted square-planar geometry was established by X-ray diffraction analysis. The molecules in the crystal structure of the Cu[(2-O^–)(5-NO₂)C₆H₃N–CH=CH–⁺PPh₃]₂ · 2CHCl₃ solvate are bound via hydrogen bonds of two types, namely, C(sp ²)–H···O and C(sp ³)–H···O.     

Thermal reduction and reoxidation of spinel-type Cu1−xZnxAl2O4

The thermochemical reactivity of the spinel-type quaternary metal oxide Cu_1–xZn_xAl₂O₄ has been investigated for different Cu:Zn ratios. In oxygen or inert gas atmospheres no considerable reduction is observed. In molecular hydrogen metal selective reduction of the Cu is found at relatively high temperature. The solid reduction product is made up of sintered, poorly dispersed metallic copper on a Zn-Al-O metal oxide support, a potential catalyst for the methanol synthesis. Owing to the measured high reduction temperature leading to the mentioned sintering of the metallic copper, the activity of this system cannot be high.Financial support by the Swiss National Science Foundation under project Nr. 2027933.89 is gratefully acknowledged.     

Novel coordination compounds of quinic acid. X-ray diffraction study of copper(II) complexes where the metal ion was a chiral centre

Summary The synthesis and characterization of the following coordination compounds derived from quinic acid (quin) (1): [Cu(quin)Cl(H₂O)]_n·(H₂O)_n(2); [Ni(quin)Cl(H₂O)]_n·(2H₂O) n (3); [Co(quin) Cl(H₂O)]_n·(2H₂O)_n(4); [Cu(quin) (NO₃)(H₂O)]_n·(2H₂O)_n(5); [Cu(quin)(AcO)(H₂O)]_n· (2H₂O)_n(6); [Cu(quin)H₂O]₂·2H₂O(7); [Co(quin)₂]_n (8); [Zn(quin)₂](9); [Cd(quin)₂](10) and [Hg(quin)₂]· 4H₂O (11) is presented. All of the compounds were characterized by i.r. and u.v. spectroscopy; in addition, (9) and (10) were analysed by n.m.r., and (2), (5) and (7) by X-ray crystallography. Due to the polyfunctionality of quinic acid diverse structures were obtained: (2) –(6) and (8) were polymeric, (7) was dimeric and (9) –(11) were spiranic. In compound (2) the Cu had a distorted octahedral structure; it was a chiral centre with six different substituents and an optically active ligand. Only one stereoisomer (OC-6-25-A) of the 30 possible was observed in the crystal. Compound (5) was also polymeric, the hexacoordinated Cu atom was a chiral centre (OC-6-53C) and only one stereoisomer was observed. It was bonded to three quinic acid ligands in three different coordination modes and each quinic acid was in turn bonded to three different Cu atoms. Each chain was linked to another two chains giving a net structure. Compound (7) was a dimer with two square pyramidal Cu atoms. Two apical water molecules were found in acis arrangement. Each quinic acid ligand was bonded to two Cu atoms which were linked by two oxygen bridges and each Cu atom was bonded to two quinic acid moieties.