Different structural types of copper(II) furan- and thiophencarboxylates: X-ray structural,EPR, spectral and magnetic analyses

Synthesis and characterization of eight new complexes of various structural types are reported. With 5-nitro-2-furancarboxylic acid (5-NO₂-2-fucH), two monomeric complexes, [Cu(5-NO₂-2-fuc)₂(H₂O)₂] (II) and [Cu(5-NO₂-2-fuc)₂(H₂O)₄] (III), as well as a dimeric complex with ethylnicotinate (Etnic), [Cu(5-NO₂-2-fuc)₂(Etnic)₂]₂ (V), were prepared. With other acids: 2,5-dimethyl-3-furancarboxylic acid (2,5-Me₂-3-fucH), 2-thiophencarboxylic acid (2-tpcH), 3-methyl-2-thiophencarboxylic acid (3-Me-2-tpcH) or 5-methyl-2-thiophencarboxylic acid (5-Me-2-tpcH), only dimeric complexes [Cu(2,5-Me₂-3-fuc)₂(H₂O)]₂ (I), [Cu(2,5-Me₂-3-fuc)₂(Etnic)]₂ (IV), [Cu(2-tpc)₂(Etnic)]₂ (VI), [Cu(3-Me-2-tpc)₂(Etnic)]2 (VII) and Cu(5-Me-2-tpc)₂(Etnic)]₂ (VIII) have been synthesised. Characterizations of the complexes were based on elemental analysis and infrared, electronic, EPR and magnetic measurements. Moreover, complexes III, V, VII and VIII were also studied by X-ray structural analysis. Two structural types of dimeric complexes were observed differing in the number of carboxylate bridges. Most of the dinuclear complexes exhibit the common “paddle-wheel” structural motif while the molecular structure of V contains two pentacoordinated copper(II) ions bridged by two carboxylate groups of two 5-nitro-2-furancarboxylate ligands resulting in the intramolecular copper-copper distance of 4.4960(8) Å. Magnetic properties (monomeric EPR signal and isotropic exhchange constant (J of approximately 0 cm^?1) of V confirmed a very weak magnetic interaction between copper centres.     

SOD mimetic activity of salicylatocopper complexes

Investigation of salicylatocopper complexes in the presence of a nitrogen donor ligand is a growing research area due to the interesting mimetic activities of such complexes. Here, three X-salicylatocopper (where X = 3-methyl, or 4-methoxy) complexes with three different N-donor ligands, [Cu(μ-menia)(3-Mesal)₂(menia)(H₂O)]₂ (I), Cu(3-Mesal)₂(denia)₂(H₂O)₂ (II), Cu(4-MeOsal)₂(2-pyme)₂ (III), are presented (where 3-Mesal = 3-methysalicylate, 4-MeOsal = 4-methoxysalicylate, menia = N-methylnicotinamide, 2-pyme = 2-pyridylmethanol). The complexes were characterized by elemental analysis, IR and UV-VIS spectrophotometry. Cyclic voltammetry and the superoxide dismutase activity of the prepared complexes in solution were measured and the complexes were characterized by means of the inhibition concentration IC₅₀. In addition, the superoxide dismutase (SOD) activity of these complexes was compared with those of the parent ligand copper acetate, native SOD enzyme, and the related copper complexes containing non-steroidal anti-inflammatory drugs. The resulting SOD activity was correlated to the composition, structure and redox stability of the prepared complexes. The best value of the inhibition concentration was found for complex I (IC₅₀ = 2.24 µM), which classifies this complex into a group of good superoxide scavengers.     

Self-assembly hydrogen-bonded supramolecular arrays from copper(II) halogenobenzoates with nicotinamide: Structure and EPR spectra

Nicotinamide was employed as a supramolecular reagent in the synthesis of six new copper(II) bromo-, iodo-, fluoro- and dibromobenzoate complexes. Structures of [Cu(2-Brbz)₂(nia)₂(H₂O)₂] (I), [Cu(2-Ibz)₂(nia)₂(H₂O)2] (II), [Cu(2-Fbz)₂(nia)₂(H₂O)₂] (III), [Cu(4-Brbz)₂(nia)₂(H₂O)₂] (IV), [Cu(3,5-Br₂bz)2(nia)₂(H₂O)2] (V), [Cu(F-Fbz)₂(nia)₂(H₂O)] · H₂O (VI) (nia = nicotinamide, 2-Brbz = 2-bromobenzoate, 4-Brbz = 4-bromobenzoate, 3,5-Br₂bz = 3,5-dibromobenzoate, 2-Ibz = 2-iodobenzoate, 2-Fbz = 2-fluorobenzoate, 4-Fbz = 4-fluorobenzoate) were determined using X-ray analysis. Compound [Cu(2-Brbz)₂(nia)₂] · 2H₂O (VII) was prepared by a new method and also characterized by X-ray powder diffraction and EPR spectroscopy. Compounds I–V are monomeric complexes with a square-bipyramidal coordination sphere around the Cu²⁺ ion. Complex VI is monomeric with coordination environment around the Cu²⁺ ion of a tetragonal-pyramid. Complexes I and VII present examples of coordination isomerism. Molecules of all compounds are connected by N—H?O and O—H?O hydrogen bonds from the NH₂ groups of nicotinamide and water molecules which create supramolecular hydrogen-bonding-coordination chains and networks.     

Synthesis,structures and magnetic properties of three copper(II) complexes of 2-(1<Emphasis Type="Italic">H</Emphasis>-pyrazol-3-yl) pyridine

Three Cu(II) complexes: [Cu₂(μ-L)₂(HCOO)₂(H₂O)₂] (1), [Cu₂(μ-L)₂(NO₃)₂] (2), and [Cu₄(μ-L)₆(CH₃COO)₂]·2H₂O (3) constructed from 2-(1H-pyrazol-3-yl) pyridine (HL) were synthesized and structurally characterized by X-ray single-crystal diffraction. The X-ray analyses revealed that all three complexes feature a di-ligand-bridged Cu₂ unit, which is nearly planar. Each deprotonated ligand chelates one copper atom by means of N,N(pyridine-pyrazole) pocket and simultaneously bridges the other one by the N,N(pyrazole) groups. The remaining coordination sites of the Cu(II) centers are either occupied by different anionic coligands to balance the charge, or bridged by another L to develop a tetranuclear structure. Magnetic investigations reveal that the distortion of the Cu(II) coordination geometry (as described by the τ values) and the coplanarity of the Cu–(N=N)₂–Cu unit have cooperative effects on the antiferromagnetic strength of these systems.     

Azidokomplexe in nicht-wäßrigen Lösungen, 1. Mitt.: Co(II), Ni(II) und Cu(II) in Acetonitril,Trimethylphosphat und Dimethylsulfoxid

The formation of azido complexes is investigated inDMSO, TMP andAN by spectrophotometric, potentiometric (Tl/TlN₃-electrode) and conductometric methods. The following coordination forms were established: [CoN₃]⁺ (octahedral, inTMP), [Co(N₃)₂] (tetrahedral, inTMP, AN andDMSO), [Co(N₃)₄]^2? (tetrahedral, inTMP, AN andDMSO); Ni(N₃)₂ and [Ni(N₃)₄]^2? (either, inTMP, AN andDMSO), [CuN₃]⁺ and [Cu(N₃)₂] (both inTMP, AN andDMSO), [Cu(N₃)₃]^? (tetrahedral, inTMP andAN) and [Cu(N₃)₄]^2? (tetrahedral, inTMP, AN andDMSO).     

Chloro- und Azidokomplexe des Vanadyl(IV)-Ions in Acetonitril,Propandiol-1,2-carbonat,Trimethylphosphat und Dimethylsulfoxid

The formation of chloro- and azidocomplexes of VO²⁺(IV) is investigated in acetonitrile (AN), propanediol-1,2-carbonate (PDC), trimethyl phosphate (TMP) by spectrophotometric, potentiometric and conductometric methods. The following coordination forms are indicated: [VOCl]⁺ inAN, PDC andDMSO), [VOCl₂] (inAN, PDC andTMP), [VOCl₃]^? (inPDC andTMP[?]), [VOCl₄]^2? (inAN, PDC andTMP); [VON₃]⁺ (inAN, PDC andDMSO), [VO(N₃)₂] (inAN, PDC, TMP andDMSO), [VO(N₃)_2+n]^n? (inAN, PDC, TMP andDMSO). The results are interpreted by the donor numbers and sterical properties of the solvent molecules.     

Structural studies of nickel(II) complexes with 1-<Emphasis Type="Italic">tert</Emphasis>-butylimidazole-2-thione and 3-phenyl-5-methyl-pyrazole ligands

The nickel(II) complexes dichlorobis(1-tert-butylimidazole-2-thione)nickel(II) [Ni(tm ^t-Bu)₂Cl₂] (1), dinitratobis(1-tert-butylimidazole-2-thione)nickel(II) [Ni(tm ^t-Bu)₂(NO₃)₂] (2), dichloro-bis(3-phenyl-5-methyl-pyrazole)(1-tert-butylimidazole-2-thione)nickel(II) [Ni(pz^Ph,MeH)₂(tm ^t-Bu)Cl₂] (3) and dinitratobis(3-phenyl-5-methyl-pyrazole)(1-tert-butylimidazole-2-thione)nickel(II) [Ni(pz^Ph,MeH)₂(tm ^t-Bu)(NO₃)₂] (4) have been synthesized and studied. The single crystal X-ray diffraction analysis was carried out for 1 and 4 {Bruker Kappa Apex-II CCD diffractometer, MoK _α radiation}. Crystal data for 1: monoclinic C2/c, a = 16.949(2) Å, b = 8.6647(10) Å, c = 15.461(3) Å, β = 117.662(4)°, V = 2011.1(5) ų, Z = 4, D _calc = 1.460 g/cm³. Crystal data for 4: triclinic P-1, a = 9.9775(7) Å, b = 11.2254(8) Å, c = 14.8068(10) Å, α = 75.401(4)°, β = 87.422(4)°, γ = 74.874(4)°, V = 1548.86(19) ų, Z = 2, D _calc = 1.405 g/cm³. Coordination core of complex 1 adopts distorted tetrahedral geometry whereas core 4 has distorted octahedral geometry. The bonded nitrates are of two types coordinating as monodentate and bidentate ligands.     

New binuclear copper(II) complexes [Cu<Subscript>2</Subscript>(L)<Subscript>4</Subscript>(μ-CO<Subscript>3</Subscript>)][B<Subscript>12</Subscript>H<Subscript>12</Subscript>] (L = bipy,phen): Synthesis,structure, and magnetic properties

The processes taking place in the Cu^I/L/solv system (L = bipy, phen) in the presence of the [B₁₂H₁₂]^2– anion, which exhibited the lowest reducing ability among the [B _n H _n ]^2– cluster anions (n = 6, 10, 12), were studied. The binuclear complexes [Cu₂(L)₄(μ-CO₃)][B₁₂H₁₂] · n(solv) were found to be formed upon the redox reaction of (C₆H₅)₄P[Cu[B₁₂H₁₂]] with a twofold excess of L or the reaction of copper(II) complex [(Cu₂(phen)₄(CO₃)]Cl₂ with [(C₄H₉)₃NH]₂[B₁₂H₁₂]. The Cu(II) complexes were characterized by X-ray diffraction; their EPR-spectra were studied at 295 K and the magnetic measurements were performed in the 300–2 K range. In the [Cu₂(phen)₄(μ-CO₃)][B₁₂H₁₂] · DMF dimer with the anti-anti coordination of the (μ-CO₃)-group, strong antiferromagnetic interactions occur between the Cu(II) atoms (Cu?Cu = 5.107 Å).     

Density functional theory study of UO<Stack> <Subscript>2</Subscript> <Superscript>2+</Superscript> </Stack> solvation in 1-butyl-3-methylimidazolium chloride

Structural characteristics and energies of [UO₂Cl₄(BMIm)_n]^(n–2)+ (n = 1-4) solvation complexes have been studied by the density functional theory (DFT) method in the SVWN5 local functional approximation.     

Formation of mononuclear rhodium(III) sulfates: <Superscript>103</Superscript>Rh and <Superscript>17</Superscript>O NMR study

It was shown that the monomeric rhodium sulfate complexes [Rh(H₂O)₄(SO₄)]⁺, trans-[Rh(H₂O)₂(SO₄)₂]^?, cis-[Rh(H₂O)₂(SO₄)₂]^?, and [Rh(SO₄)₃]^3? were not predominant forms in aqueous solutions. The ¹⁰³Rh NMR chemical shifts of the complexes were assigned, and the conditions for their formation in solutions, concentration parameters, and acidity at which the fraction of the monomers was maximal were determined. The constants of formation of the complexes and ion pair (IP) were estimated: K _IP = 8 ± 3.5, K ₁ ≈ 8, K _2trans ≈ 1, K _2cis ≈ 1, and K ₃ ≈ 2.     

Crystal structure determination,and DFT Calculations of dichlorobis-(dimethylsulfoxide-O)copper(II)

The crystal structure of dichlorobis(dimethylsulfoxide-O)copper(II), [CuCl₂(DMSO)₂] (I), previously determined by Willett and Chang, is reinvestigated. It crystallizes in the orthorhombic system with the space group Pnma (N°62), Z = 4, and unit cell parameters a = 8.053(1) Å, b = 11.642(5) Å, c = 11.347(3) Å. Our structure determination is of a significantly higher precision in terms of bond lengths, angles, and R factors (e.g., Cu1–O1 = 1.9737(24) Å, O1–Cu1–O1ⁱ = 173.08(13)° (symmetry code: ^I x, 1/2–y, z) and R(F ²) = 0.046 compared to 1.955(4) Å, 173.0(3)° and R(F) = 0.075). In contrast to the previous investigation, all H atoms are placed at calculated positions. In the title molecule, the Cu^II atom is five coordinated in a distorted square pyramidal geometry. Thus, as reported previously, it can be shown that the crystal structure consists of [CuCl₂(DMSO)₂] molecules which, by virtue of long Cu–Cl interactions, are tied together to form chains parallel to the [100] direction. The density functional theory (DFT) optimized structure at the B3LYP/6-311++G(2d,2p) level is compared with the experimentally determined molecular structure. The HOMO-LUMO energy gap and other related molecular properties are also calculated. Comprehensive experimental and theoretical structural studies on the studied complex are carried out by FT-IR and UV-visible spectroscopies.     

Onium Sulfates and Hydrogen Sulfates: Products of Reactions of Sulfur(IV) Oxide with Aqueous Solutions of Alkylamines and Aniline

The reaction products formed in the SO₂–L–H₂O–O₂ systems (L is n-propylamine, n-butylamine, tert-butylamine, n-heptylamine, n-octylamine, aniline) were isolated and identified as “onium” salts [n-C₃H₇NH₃]₂SO₄, [n-C₄H₉NH₃]₂SO₄, [t-C₄H₉NH₃]₂SO₄, [n-C₇H₁₅NH₃]₃SO₄(HSO₄), [n-C₈H₁₇NH₃]₃SO₄(HSO₄), and [C₆H₅NH₃]₂SO₄. The products were characterized by elemental analysis, IR and Raman spectroscopy, mass spectrometry, and thermogravimetry.     

Chlorokomplexe von 3 d5-Ionen in nichtwäßrigen Lösungen

The chloro systems of Mn²⁺ and Fe³⁺ were investigated in acetonitrile (AN), propanediole-1,2-carbonate (PDC) and trimethylphosphate (TMP) by spectrophotometric, potentiometric and conductometric methods. The following coordination forms seem to be present: MnCl₂ (inAN, PDC andTMP), [MnCl₄]^2? (tetrahedral inAN, octahedral inTMP), [MnCl₆]^4? (octahedral inPDC andTMP); [FeCl]²⁺ (tetrahedral inAN andPDC), [FeCl₂]⁺ (tetrahedral inTMP), FeCl₃ (tetrahedral inAN andPDC), [FeCl₄]^? (tetrahedral inAN, PDC andTMP).     

Hydrothermal synthesis and crystal structure of a composite complex constructed from Keggin-type tungstoborate and copper

A novel composite complex constructed from Keggin-type tungstoborate and copper, [Cu(En)₂(H₂O)][Cu(En)₂]₂H₃[BW_11.75Cu_0.25O₄₀] · 3.75H₂O (I), where En is ethylenediamine, has been synthesized hydrothermally and characterized by elemental analysis, IR, XPS, TGA, and single-crystal X-ray diffraction. The crystal structure of I consists of one Keggin polyoxoanion [BW_11.75Cu_0.25O₄₀]^6?, one cation [Cu(En)₂(H₂O)]⁺, two cations [Cu(En)₂]⁺, three protons, and 3.75 lattice water molecules. Compound I crystallizes in the orthorhombic, space group Pbca, a = 21.5438(18), b = 20.6591(18), c = 26.052(2) Å, V = 11595.2(17) ų, Z = 8, ρ = 3.968 g/cm³, F(000) = 12322, μ = 24.476 mm^?1, R = 0.0306 and wR = 0.0666.     

Self assembly of three new copper coordination polymers based on N-[(3-pyridine)-sulfonyl]aspartate: Synthesis and structure

Three new copper coordination polymers [Cu(L) · 6H₂O] _n (I), [Cu₂(L)₂] _n (II), and [Cu(HL)₂] _n (III), where H₂L is N-[(3-pyridine)-sulfonyl]aspartate, have been synthesized and characterized by singlecrystal X-ray diffraction (CIF files CCDC nos. 1435871 (I), 1435872 (II), 1435873 III), elemental analysis and IR spectra. Moreover, the variable-temperature magnetic susceptibility had been studied for complex I. A structural comparison of these polymers suggests that different reaction temperatures play important role in the construction of resulting architectures for I–III.     

Synthesis and catalytic reactivity of mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes

The reactions of five dinuclear carbonyl complexes [(η ⁵-C₅Me₄R)Mo(CO)₃]₂ [R = allyl, ⁿ Bu, ^t Bu, Ph, Bz] with I₂ in chloroform solution gave the corresponding mononuclear substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes [(η ⁵-C₅Me₄R)MoI(CO)₃] [R = allyl (1), ⁿ Bu (2), ^t Bu (3), Ph (4), Bz (5)]. The molecular structures of complexes 2, 3 and 5 were determined by X-ray diffraction analysis. The results show that the substituent in the ring can directly affect the Mo–I bond distances; the more sterically hindered the substituent, the longer the Mo–I bond. Friedel–Crafts reactions of aromatic compounds with a variety of alkylation reagents catalyzed by the complexes showed that all of these mononuclear molybdenum carbonyl complexes have catalytic activity in Friedel–Crafts alkylation reactions. Indeed, compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as higher activities, mild reaction conditions, high selectivity, simple post-processing, and environmentally friendly chemistry.     

Synthesis and crystal structure of triaqua[0.25(bromo)1.75(nitrato-O)]copper(II) 18-crown-6 hydrate (solvate)

A complex triaqua[0.25(bromo)1.75(nitrato-O)]copper(II) 18-crown-6 hydrate (solvate), [CuBr_0.25(NO₃)_1.75(H₂O)₃] · 18-crown-6 · 5H₂O, is synthesized, and its crystal structure is studied by X-ray diffraction analysis (space group Cmc2₁, a = 13.705, b = 14.583, c = 13.174 Å, Z = 4; direct method, full-matrix least-squares refinement in the anisotropic approximation to R = 0.069 for 2547 independent reflections; CAD-4 automated diffractometer, λMoK _α radiation). The mixed complex molecule is a randomly disordered mixture of [Cu(NO₃)₂(H₂O)₃] and [CuBr(NO₃)(H₂O)₃] molecules with site occupancies of 0.875 and 0.125, respectively. The mixed complex molecule and 18-crown-6 molecule lie on the m plane. In the main complex molecule [Cu(NO₃)₂(H₂O)₃], the coordination polyhedron of the Cu²⁺ cation is a slightly distorted square pyramid. The 18-crown-6 molecule has the conformation of a crown with the approximate symmetry D _3d .     

Crystal structures of <Emphasis Type="Italic">trans</Emphasis>-[Re<Subscript>6</Subscript>S<Subscript>8</Subscript>(CN)<Subscript>2</Subscript>L<Subscript>4</Subscript>] complexes,L = pyridine or 4-methylpyridine

The structures of three novel octahedral rhenium cluster compounds [Re₆S₈(CN)₂(py)₄]·H₂O (1), [Re₆S₈(CN)₂(4-Mepy)₄] (2), [Re₆S₈(CN)₂(4-Mepy)₄]·4-Mepy (3) (py = pyridine, 4-Mepy = 4-methylpyridine) are determined by X-ray crystallography. Crystal data are: C2/m space group, a = 14.813(1) Å, b = 14.772(1) Å, c = 9.2122(6) Å, β = 119.085(2)°, V = 1761.7(2) ų, d _x = 3.318 g/cm³, R = 0.0585 (1); I4₁/amd space group, a = 16.0018(3) Å, c = 14.7186(5) Å, V = 3768.81(16) ų, d _x = 3.169 g/cm³, R = 0.0489 (2); P2₁/c space group, a = 9.0452(4) Å, b = 15.8065(7) Å, c = 15.2951(6) Å, β = 103.700(2)°, V = 2124.57(16) ų, d _x = 2.957 g/cm³, R = 0.0245 (3). Molecular cluster complexes interact via π-π stacking affording 3D frameworks in 1 and 2 and chains in 3.     

Synthesis and crystal structures of two silver(I) complexes derived from 2-amino-6-methylpyridine with nicotinic acid and isonicotinic acid

The reaction of Ag₂O and 2-amino-6-methylpyridine (AMP) with nicotinic acid (HNA) and isonicotinic acid (HINA), respectively, afforded two silver(I) complexes, [Ag₂(NA)₂(AMP)₂] _n (I) and [Ag₂(INA)₂(AMP)₂] _n (II). Both complexes were characterized by elemental analyses and X-ray single-crystal diffraction. Complex I is a pyridine-3-carboxylate bridged polynuclear silver(I) complex, in which the Ag atom is in a tetrahedral geometry, while complex II is a pyridine-4-carboxylate bridged polynuclear silver(I) complex, in which the Ag atom is in a distorted T-shaped geometry. The crystal of I is monoclinic: space group P2₁/c, a = 8.079(2), b = 17.150(3), c = 8.912(2) Å, β = 98.106(2)°, V = 1222.5(5) ų, Z = 4. The crystal of II is monoclinic: space group P2₁/c, a = 7.225(1), b = 12.049(1), c = 15.053(2) Å, β = 102.050(1)°, V = 1281.6(3) ų, Z = 4.     

DNA binding,antibacterial and antifungal activities of copper(II) complexes with some S-alkenyl derivatives of thiosalicylic acid

The biological activities of two binuclear copper(II) complexes containing S-alkenyl derivatives of thiosalicylic acid are reported [alkenyl = propenyl (L1), isobutenyl (L2)]. The structure of the complex with the S-isobutenyl derivative (C2) was confirmed by single-crystal X-ray structure analysis, which revealed that the structure consists of centrosymmetric, dinuclear complex molecules [Cu₂(S-i-butenyl-thiosal)₄(DMSO)₂] containing two Cu(II) centers bridged by four S-isobutyl-thiosalicylate ligands in a paddle-wheel type structure. The Cu(II) atom is situated in a distorted square-pyramidal environment formed by carboxylate oxygen atoms in the basal plane and a DMSO ligand in the axial position. The reactivities of the complexes toward guanosine-5′-monophosphate (5′-GMP) were investigated. Complex C2 ([Cu₂(S-i-butenyl-thiosal)₄(H₂O)₂]) reacted more rapidly with 5′-GMP than complex C1. The interactions of complexes C1 and C2 with calf thymus DNA (CT-DNA) were examined by absorption (UV–Vis) and emission spectral studies (ethidium bromide displacement studies), revealing good DNA interaction abilities. The antimicrobial activities of the free ligands and their complexes were tested by microdilution method, and both minimal inhibitory and microbicidal concentrations were determined. All the tested substances demonstrated selective and moderate antibacterial activity on gram-positive bacteria, but low antibacterial activity on gram-negative bacteria. Also, the tested substances demonstrated low antifungal activity.