2H2O In Methanol Research Articles

Crystal structure of a solvated dinuclear CuII complex derived from 3,3,3′,3′-tetraethyl-1,1′-(furan-2,5-dicarbonyl)bis(thiourea)

Reaction between equimolar amounts of 3,3,3′,3′-tetraethyl-1,1′-(furan-2,5-dicarbonyl)bis(thiourea) (H2L) and CuCl2·2H2O in methanol in the presence of the supporting base Et3N gave rise to a neutral dinuclear complex bis[μ-3,3,3′,3′-tetraethyl-1,1′-(furan-2,5-dicarbonyl)bis(thioureato)]dicopper(II) dichloromethane disolvate, [Cu2(C16H22N4O3S2)2]·2CH2Cl2 or [Cu2(L)2]·2CH2Cl2. The aroylbis(thioureas) are doubly deprotonated and the resulting anions {L 2–} bond to metal ions through (S,O)-chelating moieties. The copper atoms adopt a virtually cis-square-planar environment. In the crystal, adjacent [Cu2(L)2]·2CH2Cl2 units are linked into polymeric chains along the a-axis direction by intermolecular coordinative Cu...S interactions. The co-crystallized solvent molecules play a vital role in the crystal packing. In particular, weak C—Hfuran...Cl and C—Hethyl...Cl contacts consolidate the three-dimensional supramolecular architecture.

Copper(II) Complexes Supported by Bis(imino)pyridine Ligands: Synthesis and Catalysis on Azide‐Alkyne Click Reactions

AbstractThe synthesis, characterization and catalytic activity of copper(II)‐bis(imino)pyridine pincer complexes were described. The copper(II) complexes (2 a and 2 b) were synthesized by the reaction of 2,6‐bis(imino)pyridine ligands with CuCl2 ⋅ 2H2O in methanol as a solvent. The copper(II) complexes were fully characterized by IR, UV‐Visible, Mass spectroscopy and elemental analysis. The copper(II) complexes 2 a and 2 b showed excellent catalytic activity towards azide‐alkyne cycloaddition (Click reaction) in water and produced regioselective product of 1,4‐disubstituted‐1,2,3‐triazoles. The copper(II) complex (2 b) with electron withdrawing CF3 group exhibited comparatively higher catalytic activity in azide‐alkyne cycloaddition reactions and produced up to 93 % of yield with 0.05 mol % of the catalyst loading.

Cu(II)-Hydrazide Coordination Compound Supported on Silica Gel as an Efficient and Recyclable Heterogeneous Catalyst for Green Click Synthesis of β-Hydroxy-1,2,3-triazoles in Water.

A hydrazone ligand, (E)-6-(2-((2-hydroxynaphthalen-1-yl)methylene)hydrazinyl)nicotinohydrazide (H2L), was synthesized and characterized by spectroscopic methods. The reaction of H2L with CuCl2·2H2O in methanol gave Cu(II) coordination compound, [Cu(HL′)(Cl)]·CH3OH (1), which was characterized by elemental analysis and spectroscopic methods (Fourier transform infrared (FT-IR) and UV–vis). The structure of 1 was also determined by single-crystal X-ray analysis. Structural studies confirmed the formation of esteric group during the synthesis of 1. Compound 1 was immobilized on 3-aminopropyltriethoxysilane (APTS)-functionalized silica gel through the amidification reaction and the obtained heterogeneous coordination compound was utilized as a catalyst for the three-component azide–epoxide–alkyne cycloaddition reaction in water as a green solvent. The structural properties of the heterogeneous catalyst were characterized by a combination of FT-IR, UV–vis, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS) analyses. The effect of the amount of catalyst and temperature on the cycloaddition reaction was studied, and the obtained 1,2,3-triazoles were characterized by spectroscopic studies and single-crystal X-ray analysis. The catalytic investigations revealed that this catalytic system has high activity in the synthesis of β-hydroxy-1,2,3-triazoles. It was also found that the aromatic and aliphatic substituents on the alkyne and epoxide together with the reaction temperature have considerable effects on the activity and regioselectivity of this catalytic system.

Copper complexes of 1,4-diazabutadiene ligands: Tuning of metal oxidation state and, application in catalytic C-C and C-N bond formation

Reaction of 1,4-diazabutadiene (p-RC6H4N = C(H)(H)C = NC6H4R-p; R = OCH3, CH3, H and Cl; abbreviated as L-R) with CuCl2·2H2O in methanol at ambient temperature (25 °C) affords a group of doubly chloro-bridged dicopper complexes of type [{CuI(L-R)Cl}2], designated as 1-R. Similar reaction carried out in acetonitrile furnishes a family of doubly chloro-bridged dicopper complexes of type [{CuII(L-R)Cl2}2], designated as 2-R. Molecular structures of 1-OCH3 and 2-OCH3 have been determined by X-ray crystallography. While copper(I) is having a nearly tetrahedral N2Cl2 coordination sphere in 1-OCH3, the N2Cl3 coordination sphere around copper(II) is distorted square pyramidal in nature in 2-OCH3. Isolated 2-R complexes, on dissolution in methanol, are found to undergo facile reduction of the metal center to generate the corresponding 1-R complexes. The 1-R and 2-R complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the 1-R and 2-R complexes shows both metal-centered and ligand centered redox responses. The 1-R complexes are found to efficiently catalyze C-N cross-coupling reactions between arylboronic acids and aryl amines; while the 2-R complexes display notable catalytic efficiency for nitroaldol reactions.

Syntheses and Crystal Structures of 2-Chloromethyl-3,5-dimethyl-4-methoxy/ethoxy-pyridines and Their Methylsulphinyl Derivatives

Treatment of 2-(chloromethyl)-pyridine derivatives 3,5-dimethyl-4-(alkoxy)-2-(chloromethyl)-pyridine hydrochloride (alkoxy = methoxy, 1; ethoxy, 2) with 1-(4-chloro-phenyl)imidazole-2-thione in the presence of sodium methoxide afforded the corresponding methylsulphinyl derivatives 3,5-dimethyl-[4-(alkoxy)-2-pyridinyl]-methylthio-1-(4-chloro-phenyl)-imidazole (alkoxy = methoxy, 3; ethoxy, 4). Similarly, reaction of 1 or 2 with 4,6-dimethyl-pyrimidine-2-thiol gave the methylsulphinyl derivatives 3,5-dimethyl-[4-(alkoxy)-2-pyridinyl]-methylthio-4,6-dimethyl-pyrimidine (alkoxy = methoxy, 5; ethoxy, 6). While reaction of 5 with CuCl2·2H2O in methanol produced a square-planar copper(II) complex, trans-bis{3,5-dimethyl-[4-(methoxy)-2-pyridinyl]-methylthio-4,6-dimethyl-pyrimidine}-dichloro-copper(II) (7). The crystal structures of 1, 2, 4⋅HCl⋅2H2O, and 7, along with their spectroscopic properties are reported. The weak hydrogen-bonding interactions exist in compounds 1, 2, and 4⋅HCl⋅2H2O. Compound 1 crystallizes in the monoclinic space group P21/c with a = 6.074(11), b = 19.88(4), c = 9.230(16) A, β = 99.67(4)°, and Z = 4. Compound 2 crystallizes in the monoclinic space group P21/n with a = 10.0103(15), b = 7.9905(12), c = 15.120(2) A, β = 93.924(2), and Z = 4. The unit cells of both 4⋅HCl⋅2H2O and 7 have triclinic P-1 symmetry with the cell parameters a = 7.492(8), b = 10.170(12), c = 15.723(18) A, α = 77.159(15)°, β = 91.113(13)°, γ = 81.194(16)°, and V = 1152(2) A3 for 4⋅HCl⋅2H2O and a = 10.526(2), b = 12.936(2), c = 14.455(3) A, α = 107.929(2)°, β = 93.686(2)°, γ = 104.095(3)°, and V = 1734.3(6) A3 for 7. Interaction of 3,5-dimethyl-[4-(methoxy)-2-pyridinyl]-methylthio-4,6-dimethyl-pyrimidine and CuCl2·2H2O in methanol resulted in the formation of a square-planar copper(II) complex, trans-bis{3,5-dimethyl-[4-(methoxy)-2-pyridinyl]-methylthio-4,6-dimethyl-pyrimidine}-dichloro-copper(II), which was structurally characterized.

A New Trinuclear Zn(II) Complex {[Zn(μ-ONN)(μ2-O)(μ-OO)]2Zn}: Synthesis, Characterization, Thermal Decomposition and Antibacterial Activity

New centrosymmetric trinuclear zinc(II) complex {[Zn(μ-ONN)(μ2-O)(μ-OO)]2Zn} has been synthesized by the reaction of a potentially ONN tridentate Schiff base ligand, and N,N-dimethylethylendiamin, with Zn(OAc)2·2H2O in methanol, in the refluxed conditions and characterized by elemental analysis, FT-IR and UV–Vis spectroscopy. Single crystal X-ray structure analysis reveals a trinuclear complex {[Zn(μ-ONN)(μ2-O)(μ-OO)]2Zn} with zinc(II) ions connected by three different bridges, (μ-ONN) of the Schiff base ligand, μ2-O and μ-OO of the acetate. The complex is centrosymmetric, with one of the Zn atoms located at the inversion center. While the central Zn(II) ion is six-coordinated, the coordination number of the other Zn(II) ions is five. Finally, the {[Zn(μ-ONN)(μ2-O)(μ-OO)]2Zn} complex was thermally decomposed in air at 700 °C resulted in ZnO nano crystalites with the average size of 42 nm. The antibacterial activity of ligand and its zinc(II) complex were tested against gram-positive and gram-negative bacteria. The ligand showed higher activity than its zinc(II) complex.

Synthesis, characterization, structure, DNA binding aspects and molecular docking study of a novel Schiff base ligand and its bis(μ-chloro) bridged Cu(II) dimer

A novel Schiff base ligand, 2-(benzothiazol-2-yl-hydrazono)-1,2-diphenyl-ethanone (LH), has been synthesized out of the 1:1 condensation of benzil and 2-hydrazino benzothiazol in methanol. Reaction of equimolar proportion of LH and pre-activated CuCl2·2H2O in methanol generates bis(μ-chloro)bis(2-(benzothiazol-2-yl-hydrazono)-1,2-diphenyl-ethanoate)-dicopper(II), [Cu2(μ-Cl)2(L)2] (1) in copious yield. C, H and N microanalyses, ESI-MS, FT-IR, UV–Vis spectral studies have been undertaken to characterize LH and 1. The X-ray crystal structure of 1 has been determined. LH undergoes keto-enol tautomerism. The tautomeric aspects of LH have been corroborated through DFT calculations. LH binds to copper(II) in its enolate form to give rise the symmetric bis(μ-chloro) bridged copper(II) dimer. Both LH and 1 show the efficacy to bind CT DNA. The binding constants and the thermodynamic binding parameters have also been determined. A favourable major groove binding efficacy has been exposed for both the ligand and complex through molecular docking.

Synthesis, Characterization and Crystal Structure of a New Schiff Base Ligand from a Bis(Thiazoline) Template and Hydrolytic Cleavage of the Imine Bond Induced by a Co(II) Cation

The reaction of bis-[2-amino-4-pheny1-5-thiazolyl] disulfide with 5-nitro-salicylaldehyde in absolute ethanol resulted in the formation of a new Schiff base ligand H2L (1). Characterization of the ligand was performed by FT-IR, 1H NMR, 13C NMR, UV-Vis, elemental analysis and single crystal X-ray diffraction. The ligand, (1), possesses a disulfide –S–S– bridge of 2.1121 (3) ? length, and the molecule adopts a cis-conformation around this bond. In the crystal structure of (1), an intramolecular O–H···N hydrogen bond with D… A distance of 2.69 (3) ? was present. The reaction of (1) with Co(NO3)2·6H2O and CuCl2·2H2O in methanol afforded the corresponding metal complexes. The obtained solids were further investigated by elemental analysis and UV-Vis titration that confirmed the formation of [CoL] and [ClCuHL] complexes. However, recrystallizaion of the Co(II) complex in dimethylsulfoxide caused the complete hydrolysis of the imine bond and afforded a Co(II) complex in which two 5-nitro-salicylaldehyde and two DMSO molecules were coordinated to the central metal in an octahedral fashion. This structure (2) was also confirmed by single crystal X-ray analysis.

A new B-Anderson-type heteropoly compound containing binuclear copper(II) coordination ions: synthesis, molecular structure and properties of [Cu2(phen)2(CH3COO)2(H2O)2] [HAl(OH)6(Mo6O18)]·2.5H2O (phen = 1,10-phenanthroline)

A new B-Anderson-type heteropoly compound [Cu2(phen)2(CH3COO)2(H2O)2] [HAl(OH)6(Mo6O18)] · 2.5H2O containing binuclear copper(II) coordination ions has been synthesized by reaction of AlCl3 · 6H2O, Na2MoO4 · 2H2O, glacial acetic acid, 1,10-phenanthroline and CuCl2 · 2H2O in methanol--water mixed solution and characterized by IR, UV-Vis spectra, TG-DTA analysis and X-ray crystallography. From X-ray single-crystal structural analysis, the title compound crystallizes in a triclinic lattice, P space group, with a = 13.379(3), b = 17.388(4), c = 18.063(4) Å, α = 85.97(3), β = 69.79(3), γ = 69.22(3)°, V = 3680.4(13) Å3, Z = 2, R 1 = 0.0797, wR 2 = 0.1787. In the title compound, the two Cu2+ coordination cations are combined with each other through two acetate bridges and have five-coordinate, distorted square-pyramid geometry with N2O3 bonding at each metal. In addition, there are also two crystallographically independent ‘one-half ’ Anderson-type polyanions in the title compound lattice.

Aerobic Oxidation of Primary Alcohols (Including Methanol) by Copper(II)− and Zinc(II)−Phenoxyl Radical Catalysts

The tetradentate ligand N,N‘-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,2-phenylenediamine, H4L1, has been prepared, and its square planar complexes [CuII(L3)] and [ZnII(L3)] have been synthesized from the reaction of H4L1 with [CuI(NCCH3)4](ClO4) or Zn(BF4)2·2H2O in methanol in the presence of air. The dianion (L3)2- represents the two-electron oxidized form of (L1)4-, namely N,N‘-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,2-diiminoquinone. Complexes [CuII(L3)]·CH3CN and [Zn(L3)]·CH3CN have been characterized by X-ray crystallography, EPR spectroscopy, and magnetochemistry; [CuII(L3)] has an S = 1/2 ground state, and [Zn(L3)] is diamagnetic. Cyclic voltammetry established that both complexes undergo two successive reversible one-electron oxidations and two successive reversible one-electron reductions. Thus, the coordinated ligand exists in five oxidation levels. The species [MII(L4)]PF6 (M = CuII, ZnII) and [MII(L5)](ClO4)2 (M = CuII, ZnII) have been isolated and characterized by UV/vis, EPR, and 1H NMR spectroscopy and by magnetic susceptibility measurements, where (L4)- represents the monoanion N-(3,5-di-tert-butyl-2-hydroxyphenyl)-N‘-(3,5-di-tert-butyl-2-phenoxyl)-1,2-diiminoquinone and (L5) is the neutral ligand N,N‘-bis(3,5-di-tert-butyl-2-phenoxyl)-1,2-diiminoquinone. Similarly, two complexes of the type [MII(L1H2)] (M = CuII, ZnII) have been isolated from the reaction of L1H4 with CuII(ClO4)2·6H2O or Zn(ClO4)2·6H2O under anaerobic conditions in the presence of NEt3. Complexes [CuII(L4)]PF6 and [Zn(L4)]PF6 selectively oxidize primary alcohols (including methanol and ethanol) in a stoichiometric fashion under anaerobic conditions, yielding the corresponding aldehydes and [MII(L2H2)]+ (M = CuII, ZnII), where (L2)3- is the trianionic form of N,N‘-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,2-diiminosemiquinone. Since the latter reduced forms react rapidly with dioxygen with formation of [MII(L4)]+ (M = Cu, Zn) and 1 equiv of H2O2, these oxidized species are catalysts for the air oxidation of primary alcohols, including ethanol and methanol, with concomitant formation of H2O2 and aldehydes. The kinetics of the stoichiometric reactions and of the catalyses (initial rate method) have been measured. Large kinetic isotope effects show that H-abstraction from the α-carbon atom of a coordinated alcoholato ligand is the rate-determining step in all cases.

Preparation and structure of 7-azaindolium salts containing unusual chloro-copper(II) anionic units

Dark-red crystals of (H2aza)5[Cu5Cl14(H2O)4]Cl were obtained by addition of HCl to equimolar amounts of 7-azaindole (Haza) and CuCl2•2H2O in methanol. They were shown by X-ray diffraction (triclinic, [Formula: see text] a = 9.396(1), b = 9.894(1), c = 15.958(1), Å, α = 106.10(1)°, β = 98.25(1)°, γ = 105.56(1)°, Z = 1, R = 0.031) to contain infinite chains in which the basic [Cu5Cl14(H2O)4]4− pattern is built up from trans-CuCl2(H2O)2, [CuCl3(H2O)]−, and dichlorobridged [Cu2Cl6]2− species. In the idealized chain, these units occur in the 1:2:1 ratio, but disorder is present and some of the CuCl2(H2O)2 units are randomly replaced by [CuCl3(H2O)]−. The Cu atoms have a roughly square-planar primary coordination, and connection along the chain is achieved by weaker apical Cu–Cl bridging interactions. All azaindole molecules are present as uncoordinated N7-protonated monocations. A related (H2aza)3[Cu3Cl8(H2O)3]Cl salt was obtained as a side-product of the reaction of 7-azaindole with excess CuCl2•2H2O in methanol without acid. In these brown crystals (triclinic, [Formula: see text] a = 9.308(1), b = 9.964(1), c = 19.212(4) Å, α = 76.67(1)°, β = 79.35(1)°, γ = 75.27(1)°, Z = 2, R = 0.046), the [Cu6Cl16(H2O)6]4− pattern of the chain contains the same three building units as above, but in the 2:2:1 ratio. In both salts, the polymeric chloro-copper chains are parallel and separated by azaindolium cations stacked along the same direction. The structures are stabilized by networks of hydrogen bonds involving the azaindolium cations, the chlorine atoms, and water molecules in the chloro-copper chain, and a noncoordinated Cl− ion. Most of the azaindolium cations are disordered. The influence of N7-protonation on the infrared spectrum of azaindole is discussed.

Some dioxouranium(VI) complexes of azo-oximes

Reactions of arylazobenzaldoximes, X-(C 6H 4)C( NOH)N NPh(HL), where X H, p-Cl, p-CH 3O, p-NO 2, or arylazoformaldoximes, HC( NOH)N N(C 6H 4Y Y(HL), where Y p-CH 3C( O) , p-Cl, p-CH 3O, p-CH 3, p-NO 2, with UO 2(OAc) 2.·2H 2O in methanol yielded complexes with the formula UO 2(L) 2·ηH 2O, where η 1–5. These dioxouranium(VI) complexes were characterized by elemental analyses, conductivity measurements, IR and 1H NMR spectroscopy. In these complexes, the azo-oximes act as bidentate ligands by bonding through the oxime-oxygen and an azo-nitrogen.