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1.
Three new mercury(II) coordination compounds, {[HgCl(pic)]}n (1), [HgCl(pic)(picH)] (2), and [HgBr(pic)(picH)] (3) (picH = pyridine-2-carboxylic acid, picolinic acid) were prepared by reactions of the corresponding mercury(II) halides and picolinic acid in an aqueous (1) or alcohol–methanol or ethanol (2 and 3) solutions. Two different types of coordination compounds were obtained depending on the solvent used. The crystal structures were determined by the single-crystal X-ray structural analysis. Compound 1 is a one-dimensional (1-D) coordination polymer with mercury(II) ions bridged by chelating and bridging N,O,O′-picolinate ions. Each mercury(II) ion is four-coordinated with a bidentate picolinate ion, a carboxylate O atom from the symmetry-related picolinate ion and with a chloride ion; the resulting coordination environment can be described as a highly distorted tetrahedron. Compounds 2 and 3 are isostructural mononuclear coordination compounds, each mercury(II) ion being coordinated with the respective halide ion, N,O-bidentate picolinate ion, and N,O-bidentate picolinic acid in a highly distorted square-pyramidal coordination environment. Compounds 1–3 were characterized by IR spectroscopy, PXRD, and thermal methods (TGA/DSC) in the solid state and by 1H and 13C NMR spectroscopy in the DMSO solution.  相似文献   

2.
《Polyhedron》1988,7(9):689-694
Protonation constants of picolinic acid and stability constants of Cu(II) and Zn(II) picolinate complexes were determined potentiometrically in 50% (v/v) dioxane-water solution at 25°C and 0.2 M KNO3. The values obtained for the constants were: protonation constants for picolinate ion: logβ1 = 5.36±0.01 and logβ2 = 6.80±0.04; stability constants for copper(II) complexes: logβ1.1 = 7.766±0.001 and logβ1.2 = 16.826±0.007; stability constants for the Zn(II) complexes: logβ1.1 = 6.10±0.05, logβ1.2 = 11.47±0.03 and logβ1.3 = 15.77±0.08. No protonated nor hydroxo-complex was detected in the metal ion-picolinate systems.  相似文献   

3.
A new dinitrogen rhenium(I) complex with a picolinate ligand has been prepared and fully characterized, providing the first example of a genuine NN complex bearing a carboxylate or a N,O-coligand. The Lever electrochemical EL ligand parameter was estimated for the first time for the picolinate ligand and shows that its carboxylate arm has a net electron-donor character similar to that of chloride, thus stabilizing the trans Re-N2 bond.  相似文献   

4.
K-band ESR spectra of 17O labelled Copper(II)oxyquinolinate (CuOX2) substituted in phthalimide single crystals and of Copper(II)picolinate (Cupic2) substituted in single crystals of Zinc picolinate tetrahydrate are reported. The spectra were analyzed as a superposition of spectra of 3 isotopic 16O, 17O species, yielding anisotropic hyperfine coupling tensors for the 17O ligands of the two complexes. The magnetic data will then be used for derivation of bonding parameters in a one hole MO scheme and of spin densities at oxygen ligands by two different approaches πo values of 0.13 and 0.085 (per oxygen atom) for CuOx2 and Cupic2 were found. f0p/f0s ratios amount to 11.0 and 8.7 for the two systems, respectively, thereby ranging considerably higher then found hitherto.  相似文献   

5.
Crystalline bis(O,O′-di-sec-butyldithiophosphato)platinum(II) was prepared and studied by means of 13C, 31P CP/MAS NMR spectroscopy and single-crystal X-ray diffraction. The unit cell of the platinum(II) compound is comprised of one centrosymmetric mononuclear molecule [Pt{S2P(O-sec-C4H9)2}2], in which the dithiophosphate groups display structural equivalence in both 31P NMR and XRD data. A pair of the dithiophosphate ligands exhibit the same S,S′-bidentate chelating structural function and form two planar four-membered chelate rings, [PtS2P], in this molecule. The planar configuration of the [PtS4] chromophore in structure 1 is governed by the dsp2-hybrid state of platinum(II). The structural states of the dithiophosphate groups in two different samples of complex 1 (one crystallised from ethanol and the other one precipitated from an aqueous solution) are all characterised by almost rhombic 31P chemical shift tensors. The observed essential dispersion of the 31P NMR chemical shift is caused by a coexistence of six optical isomers of molecule 1. The thermal behaviour of this compound was studied by means of simultaneous thermal analysis (a combination of TG and DSC) under an argon atmosphere. The thermal behaviour shows that the mass of 1 is lost in three steps, involving successive thermal decompositions of the organic and inorganic parts of this compound with platinum(II) dithio-meta-phosphate and reduced metallic platinum as the intermediate and the final products, respectively.  相似文献   

6.
ESR spectra of 17O modifications of Cu(II)picolinate substituted in Zn(II)picolinate-4H2O single crystals are reported. Values of 17O hyperfine coupling tensors, orientation angles and approximate relative spin densities at the O and N nuclei are given.  相似文献   

7.
A tin(II) squarate Sn2O(C4O4)(H2O) was synthesized by hydrothermal technique. It crystallizes in the monoclinic system, space group C2/m (no. 12) with lattice parameters a=12.7380(9) Å, b=7.9000(3) Å, c=8.3490(5) Å, β=121.975(3)°, V=712.69(7) Å3, Z=4. The crystal structure determined with an R=0.042 factor, consists of [(Sn4O10)(H2O)2] units connected from one another in the [101] and [010] directions via squarate groups to form layers separated by Sn(II) lone pairs. This compound presents the same remarkable structural arrangement as observed in the tin-oxo-fluoride Sn2[Sn2O2F4] inorganic compound with Sn(II) lone pairs E(1) and E(2) concentrated in large rectangular-shape tunnels running along [001] direction.  相似文献   

8.
Quantitative reduction of V(IV)(pic) to V(III)(pic)n and then to V(II)(pic)n(1 ⩽ n ⩽3) occurs when N2O-saturated formate solutions (pH 4.2–6.3) containing V(IV) and picolinic acid (2-carboxypyridine) are irradiated. Pulse radiolysis measurements show that CO-2 reacts with picolinate only when the N-atom is protonated (k = 2.7 × 108 dm3 mol-1 s-1). Reduction of V(IV)(pic) and V(III)(pic)n is effected by the electron adduct of the protonated picolinate (picH). with rate constants at pH 4.2 of (3.5 ± 0.2) × 107 dm3 mol-1 s-1 for V(IV)(pic) and (6.9 ± 0.4) × 108 dm3 mol-1 s-1 for V(III)(pic)n. No reduction of V(II)(pic)n is observed.  相似文献   

9.
The combination of N,N-dibromo-p-tolunesulfonamide (4-TsNBr2) and TsNH2 was found to be an efficient halogen/nitrogen source for the aminohalogenation of β-methyl-β-nitrostyrenes with manganese (II) acetate as the catalyst in the presence of 4 Å molecular sieves. The reaction results in vicinal bromoamino nitroalkanes with the opposite regioselectivity comparing with those reported, which was also confirmed by X-ray structural analysis.  相似文献   

10.
A series of zinc oxides Ln2BaZnO5 has been synthesized for Ln = Sm, Eu, Gd, Dy, Ho, and Y. Theses phases are orthorhombic and isostructural with the copper compounds Ln2BaCuO5 previously described, as shown from the structural study of one member Y2BaZnO5. In this structure, whose framework is built up from edge- and face-sharing LnO7 polyhedra, the Zn2+ ions exhibit an unusual pyramidal coordination ZnO5. The solid solution Y2BaZn1?xCuxO5 has been studied by infrared spectroscopy and electron spin resonance (ESR). The distorted square-based pyramidal configuration of Zn2+ and Cu2+ is confirmed. The ESR spectra of diluted samples exhibit a hyperfine structure and are typical of individual Cu(II) ions. For higher Cu(II) contents, they exhibit an anisotropic broad signal which is interpreted in terms of CuCu interactions.  相似文献   

11.
S-Alkyl (R = benzyl, methyl, ethyl, propyl and butyl) derivatives of thiosalicylic acid and the corresponding palladium(II) complexes were prepared and their structures were proposed on the basis of infrared, 1H and 13C NMR spectroscopy. The cis geometrical configurations of the isolated complexes were proposed on the basis of an X-ray structural study of the bis(S-benzyl-thiosalicylate)-palladium(II), [Pd(S-bz-thiosal)2] complex.Antimicrobial activity of the tested compounds was evaluated by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) in relation to 26 species of microorganisms. The tested ligands, with a few exceptions, show low antimicrobial activity. The palladium(II) complexes, [Pd(S-R-thiosal)2], have statistically significant higher activity than the corresponding ligands. The complexes [Pd(S-et-thiosal)2] and [Pd(S-pro-thiosal)2] displayed the strongest activity amongst the all tested compounds. The palladium(II) complexes show selective and moderate antibacterial activity and significant antifungal activity. The most sensitive were Aspergillus fumigatus and Aspergillus flavus.  相似文献   

12.
The reaction of the decadentate ligand tpmen (H4tpmen?=?N,N,N′N′-tetrakis[(6-carboxypyridin-2-yl)methyl]ethylenediamine) with MnCl2·4H2O in aqueous solution gives a homodinuclear complex [Mn2(H2O)2(tpmen)]·16H2O, which has been characterized by elemental analysis, thermal gravimetric and single-crystal X-ray diffraction analysis. The complex crystallizes in the orthorhombic system, space group Cmca, a?=?28.786(5) Å, b?=?11.5033(19) Å, c?=?14.437(2) Å, Z?=?8, R 1?=?0.0432, wR 2?=?0.0786. The tpmen ligand contains four picolinate groups, two of which bind each Mn(II) to form a dinuclear complex. The geometry around the Mn(II) is distorted octahedral with two nitrogen and two oxygen atoms from the picolinate groups and two oxygen atoms from coordinated water. The variable-temperature (2–300?K) magnetic susceptibilities shows an antiferromagnetic interaction between Mn(II) ions.  相似文献   

13.
The thermodynamic parameters (log K, ΔG, ΔH and ΔS) of complexation of Eu(III), a chemical analogue of trivalent actinides, with pyridine monocarboxylates, namely, picolinic acid (pyridine-2-carboxylic acid), nicotinic acid (pyridine-3-carboxylic acid), isonicotinic acid (pyridine-4-carboxylic acid) have been studied at 1.0 M ionic strength adjusted by NaClO4 and 298 K by potentiometry, fluorescence spectroscopy and calorimetry. The potentiometric results revealed formation of four complexes, MLi (i = 1–4) in case of picolinate whereas only ML complexes in case of nicotinate and isonicotinate. The log KML for Eu(III) picolinate complex is higher than that for complexes of Eu(III) with the other two acids. The complexation reaction between Eu(III) and picolinate was found to be exothermic due to chelate formation via pyridyl nitrogen. In case of complexation of Eu(III) with nicotinate and isonicotinate, the enthalpy changes are similar as in the case of simple mono carboxylates and are positive. Life time measurements by time resolved fluorescence spectroscopy, for the decay of 5D0 state of Eu(III) also indicated the formation of ML4 with picolinate and formation of ML only with the other two acids. The experimental observations on the stability and binding mode of the complexes are corroborated by theoretical calculations using the TURBOMOLE software. The detail analysis of calculated charge values of the free ligands and the complexes indicates that charge polarization is more in the isonicotinate than in nicotinate upon complexation.  相似文献   

14.
A re-examination of the oxidation of primary amines of the type R·CH2NH2 by silver(II) picolinate reveals that the major product is usually the nitrile RCN, rather than the aldehyde RCHO, as had been reported previously.4  相似文献   

15.
en Two differnt crystal modifications of hexaphenyldigermanium sulfide (C6H5GeSGe(C6H5)3 (I and II were obtained by crystallization from hot benzene/methanol or form ethanol at 20°C. Single crystal X-ray structural analyses for both I (low temperature data at ?130°C) and II (at 20°C) (I, R = 0.046; II, R = 0.048) were performed. I is monoclinic, P21/c, with a = 11.020(3), b = 15.473(3), c 18.606(3) »,π = 106.92(2)°, Z = 4; II is orthorhombic, P212121, with a = 2.617(2), b = 17.345(3), c = 18.408(3) », Z = 4.The molecules have different conformeric structures with respect to a rotation of the (C6H6)3Ge groups around the Ge bonds with very similar bond lenghts and angles. Bond data for I(II) are: GeS 2.212(1) and 2.261(1) » (2.227(2) and 2.240(2) »); GeC 1.933(4) ? 1.971(4), mean 1.945(5) » (1.931(7)?1.954(7), mean 1.943(4) »); GeSGe 111.2(1)° (110.7(1)°). The Ge bond lenghts are comparable to those in thiogermanates and do not indicate significant π-bond contributions.  相似文献   

16.
The crystal structure of the title compound, [Cu(C6H4NO2)(C2H3O2)(C3H4N2)(H2O)]·0.87H2O, has a square‐pyramidal‐coordinated CuII centre (the imidazole is trans to the picolinate N atom, the acetate is trans to the picolinate –CO2 group and the aqua ligand is in a Jahn–Teller‐elongated apical position) and has two symmetry‐independent molecules in the unit cell (Z′ = 2), which are connected through complementary imidazole–picolinate N—H...O hydrogen bonding. The two partially occupied solvent water molecules are each disordered over two positions. The disordered solvent water molecules, together with pseudosymmetry elements, support the notion that a crystal structure with multiple identical chemical formula units in the structural asymmetric unit (Z′ > 1) can represent a crystal `on the way', that is, a kinetic intermediate form which has not yet reached its thermodynamic minimum. Neighbouring molecules form π–π stacks between their imidazole and picolinate N‐heterocycles, with centroid–centroid distances in the range 3.582 (2)–3.764 (2) Å.  相似文献   

17.
A new Ni(II) layered hybrid organic-inorganic compound of formula Ni2[(NDI-BP)(H2O)2]·2H2O has been prepared in very mild conditions from N,N′-bis(2-phosphonoethyl)napthalene-1,4:5,8-tetracarboximide (NDI-BP ligand) and NiCl2. The X-ray powder structure characterization of the title compound suggests a pillared layered organic-inorganic hybrid structure. The distance between the organic and inorganic layers has been found to be 17.8 Å. The inorganic layers consist of corner sharing [NiO5(H2O)] octahedra and they are pillared by the diphosphonate groups. DC and AC magnetic measurements as a function of temperature and field indicate the presence of 2D antiferromagnetic exchange interactions between the nearest-neighbor Ni(II) ions below 100 K. A long-range magnetic ordering at Tc∼21 K has been established and is attributed to the presence of spin canting. AC magnetic measurements as a function of temperature at different frequencies confirm the occurrence of the magnetic ordering temperature at T=21 K and the presence of a slight structural disorder in the title compound.  相似文献   

18.
Several manganese (III) complexes (MnIIILx) in combination with tert-butyl hydroperoxide (t-BuOOH) activate dioxygen (O2) to oxygenate cyclohexene (c-C6H10) to its ketone, alcohol, and epoxide. The product profiles depend on the ligand and solvent matrix. With picolinate (PA), bipyridine (bpy), or triphenylphosphine oxide (OPPh3) as the ligand in py/HOAc (2:1 molar ratio) dominant product is the ketone [c-C6H8(O)] whereas Schiff–base complexes produce c-C6H8(O), c-C6H9(OH) and the epoxide in almost equal yields. However, in MeCN c-C6H8(O) is the dominant product for all of the complexes.  相似文献   

19.
The reaction of triorgano-gallium and -indium etherate with heterocyclic carboxylic acids in benzene at room temperature yields complexes of the type [R2M(L)]n(M = Ga or In; R = Me or Et; L = 2-(C5H4N)CO2, 2-(C4H3N2)CO2 or 2-(C9H6N)CO2). These complexes have been characterized by elemental analysis, IR, UV-vis, NMR (1H and 13C{1H}) and mass spectral data. Complexes with L = (C5H4N)CO2- and (C9H6N)CO2- showed photoluminescence on excitation with ∼250 or ∼310 nm radiation, respectively. Single crystal X-ray structural analysis of [Me2M(O2C-C5H4N-2)]2 (M = Ga or In), revealed a dimeric structure with five-coordinate metal atoms arising from the presence of two tridentate bridging picolinate ligands.  相似文献   

20.
EPR simulation method together with pH-potentiometry combined with UV-Vis spectrophotometry were used for the study of the ternary system 4-fuorosalicylic acid (HA)-N,N-diethylnicotinamide (B)-copper(II) in aqueous solution. The N,N-diethylnicotinamide ligand is a weak donor, its mixed-ligand complexes with 4-fluorosalicylate anions are more favoured. The number of coordinated N,N-diethylnicotinamide molecules increases with decreasing temperature: up to four ones were detected in the coordination sphere of copper(II) in frozen solutions. The formation of [CuH−1AB2] and [CuH−1A] was detected by all methods at neutral pH. At lower pH values, [CuA2B2] and [CuB] become dominant, and this fact is in good agreement with [CuA2B2(H2O)2] crystals obtained from similar solutions. The structural unit of the [CuA2B2(H2O)2] complex consists of a copper(II) ion, which is monodentately coordinated by a pair of 4-fluorosalicylate anions and by a pair of N,N-diethylnicotinamide in trans positions in the basal plane, and by two water molecules in the axial positions of a tetragonal bipyramid.  相似文献   

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