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1.
Here, we report a new type of Ng-containing compounds formed between the Ng-M group and nitrogen heterocyclic compounds, (CH2)nHNCuNg+ (n = 2, 3), (CH)4NMNg, and (CH)5NCuNg+ (M = Cu, Ag, Au; Ng = Ar, Kr, Xe). Quantum chemistry computations were carried out to optimize their geometric structures and calculate the dissociation energies, dissociation enthalpy, and dissociation free energy change. The stability of these Ng-bonding complexes was inspected by investigating the three dissociation processes of the these compounds into (a) Ng, M, and nitrogen heterocycle CnN; (b) CnN + MNg+; and (c) CnNM + Ng, which are all endothermic and nonspontaneous, these dissociation processes are also turned out to be endergonic in nature at standard state. The natural bond orbital, atoms in molecules, and energy decomposition analysis based on the molecular wavefunction show that the M-Ng and M-N bonds have some covalent and electrostatic characters.  相似文献   

2.
Copper(II) and nickel(II) biguanides and O-alkyl-1-amidinourea can act as donors for the formation of charge transfer (CT) adducts with I2 and tetracyanoquinodimethane (TNCQ) as acceptors. Iodine adducts are characterized both in solid and solution states whereas TCNQ adducts obtain only in solution. Appearance of a broad band at 355 nm for iodine adducts and at 335 nm for TNCQ adducts and shifting of i.r. frequencies support the formation of donor acceptor associates. Elemental analysis establishes 1:1 stoichiometry of the solid adducts. The K and ε values determined by modified Benesi—Hildebrand, Scott and Rose—Drago equations are found to be of the order of 104 and 103 respectively at 298 K in methanol. The solvent effect on the K values is discussed in terms of coupled solute-solute and solute-solvent equilibria.  相似文献   

3.
Li  Zhi  Shen  Xia  Zhao  Zhen 《Research on Chemical Intermediates》2022,48(1):339-349

The structures, electronic and magnetic properties of the FemOn@Cx (m?=?1–3, n?=?1–4, x?=?50, 60) clusters have been investigated by using PBE functional. The C50, C60 can significantly increase the structural stabilities of the FemOn molecules. Fe2O3@C50 and Fe3O4@C50 are more chemically stable than the Fe2O3@C60 and Fe3O4@C60 while FeO@C60 is more chemically stable than the FeO@C50. The spin densities of the FemOn fragments degenerate to zero. Carbon encapsulation leads to the internal charges of the FemOn fragments transfer from 4 s to 4p orbital.

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4.
Three pyridylbenzimidazoles (2-PBIM, 3-PBIM, and 4-PBIM) have been prepared (2-PBIM: 2-(2-pyridyl)-benzimidazole, 3-PBIM: 2-(3-pyridyl)-benzimidazole, 4-PBIM: 2-(4-pyridyl)-benzimidazole). Reactions of several transition metals (Cd2+, Cu2+, Fe2+) with the three ligands gave four new coordination complexes, [(Cd)2(2-PBIM)2(CH3COO)4] (1), [Cu(3-PBIM)2(CH3COO)2]?·?2H2O (2), [Cu(4-PBIM)2(CH3COO)2(H2O)]?·?H2O (3), and [Fe(4-PBIM)2(Cl)2(H2O)2] (4), respectively. These four complexes have been characterized by X-ray crystallography, IR spectroscopy, and UV absorption spectroscopy. Thermogravimetric properties of 2 and 4 were also measured. X-ray crystallographic studies reveal that these four complexes are very different, although the ligands are similar in structure. The role of hydrogen-bonding and π–π interactions in extending dimensionality of simple complexes has been discussed.  相似文献   

5.
Four 2-benzoylbenzoate (bba) complexes, [Co(bba)2(H2O)2(3-pic)2] (1), [Ni(bba)2(H2O)2(3-pic)2] (2), [Cu(bba)2(3-pic)2] (3), and [Hg(bba)2(3-pic)2] (4), have been synthesized and characterized by IR spectra, thermal (TG, DTG, and DTA) analysis, and single crystal X-ray diffraction. All the complexes consist of neutral monomeric units with 1 and 2 crystallizing in the orthorhombic (P n a 21), 3 in triclinic (P 1), and 4 in monoclinic (P21/c) crystal systems. The metal(II) ions exhibit distorted octahedral coordination for 1, 2, and 3 and mercury(II) exhibits distorted trigonal prism coordination. In 1 and 2, bba is monodentate, whereas in 3 and 4 bba is bidentate. 3-Picoline (3-pic) is a classical N-monodentate ligand. Bba are coordinated to metal(II) with carboxylates and IR spectra of all complexes display characteristic absorptions of carboxylate {υ(OCO)asym and υ(OCO)sym}. Thermogravimetric (TG) analyses show that 1 and 2 are thermally stable (Tdecomp.?>?60°C) and 3 and 4 are thermally stable (Tdecomp . ?>?120°C).  相似文献   

6.
The capability of mechanochemical synthesis for the formation of solid solutions of alkaline earth metal fluorides Ma1−xMbxF2 (M: Ca, Sr, Ba) was tested by fluorination of metal acetates and metal hydroxides with ammonium fluoride directly at milling. Evidence was found for a mutual substitution of cations on their lattice positions in Ca1−xSrxF2 and Ba1−xSrxF2 samples. For the Ba/Ca-system this synthesis route is only partially successful. X-ray diffraction and 19F MAS NMR spectroscopy were used to characterize all samples concerning their crystal structure and local fluorine coordination. Calculations of 19F chemical shifts with the superposition model along with probability calculations for the intensity of the individual 19F lines, performed in dependence on the molar composition of the samples, perfectly agree with the experimental findings. The fluoride ion conductivity of as-prepared samples, determined by temperature dependent DC conductivity measurements, is significantly higher than those of crystalline binary fluorides. Moreover, a higher F ion conductivity is observed for samples with higher mixing grade in the Ca/Sr-and the Ba/Sr-systems.  相似文献   

7.
8.

This work evaluates the effects of the sintering temperature (800 °C, 900 °C, 1000 °C) of SrTi1-xFexO3-δ (x = 0.35, 0.5, 0.7) porous electrodes on their electrochemical performance as potential oxygen electrode materials of solid oxide cells. The materials were prepared by a solid-state reaction method and revealed the expected cubic perovskite structure. After milling, the powders were characterised by a sub-micrometre particle size with high sinter-activity. It was shown that the lowest area specific resistance was achieved after sintering SrTi0.65Fe0.35O3 electrodes at 1000 °C, and SrTi0.5Fe0.5O3 and SrTi0.30Fe0.70O3 electrodes at 800 °C, which can be considered to be a relatively low temperature. In general, EIS measurements showed that increasing the Fe content results in lowered electrode polarisation and a decrease of the series resistance. Even though the studied materials have much lower total conductivities than state-of-the-art electrode materials (e.g. (La,Sr)(Co,Fe)O3), the polarisation resistances obtained in this work can be considered low.

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9.
Isonicotinic acid hydrazide or isonicotinylhydrazide, commonly known as isoniazid, is an antibacterial agent that has been used to treat tuberculosis. It interacts with microbial cell walls. Schiff’s bases or anils are the compounds having >C=N−N< linkages, which have immense applications as catalysts, stabilizers, pigments, dyes, and drugs. They have good ability to form chelates with many metal ions. Isoniazid can form Schiff’s bases with diketones such as acetoacetanilide. Acetoacetanilide isonicotinylhydrazone and its metal chelates exhibit anticancer activity. Our studies on N-methyl-acetoacetanilide isonicotinylhydrazone and its metal chelates revealed that they are active against pathogenic fungal strains. Hence, it is worthwhile to synthesize new complexes of ligands having different substituents on the acetoacetanilide moiety. We synthesized five new metal chelates of ω-bromoacetoacetanilide isonicotinylhydrazone. The ligand behaved as a tridentate monoanion or as a tridentate dianion in the complexes. These compounds were characterized mainly by elemental analysis; conductivity measurements; and electronic, infrared, and nuclear magnetic resonance spectral studies. We also carried out antifungal studies of these compounds against four selected pathogenic fungal strains using a cup-plate technique. Both the ligand and its metal chelates were active against all fungal strains investigated. However, the chelates were found to be more active than the ligand.  相似文献   

10.
Fluorescence spectroscopy has been used to probe the structural properties and Cu(II), Zn(II), Cd(II), and Pb(II)-binding behavior of humic acid (HA)-like fractions isolated from a municipal solid waste compost (MSWC) and HAs from unamended and MSWC-amended soils. The main feature of the fluorescence spectra, in the form of emission-excitation matrix (EEM) plots, was a broad peak with the maximum centered at an excitation/emission wavelength pair that was much shorter (340/437 nm) for MSWC-HA than for unamended and MSWC-amended soil HAs (455/513 and 455/512 nm, respectively). Fluorescence intensity for MSWC-amended soil HA was less than that for unamended soil HA. These results were indicative of more aromatic ring polycondensation and humification of soil HAs, and of partial incorporation of simple and low-humified components of MSWC-HA into native soil HA, as a result of MSWC amendment. Titrations of HAs with Cu(II), Zn(II), Cd(II), and Pb(II) ions at pH 6 and ionic strength 0.1 mol L−1 resulted in a marked decrease of the fluorescence intensities of untreated HAs. By successfully fitting a single-site fluorescence-quenching model to titration data, the metal ion complexing capacities of each HA and the stability constants of metal ion-HA complexes were obtained. The binding capacities and stability constants of MSWC-HA were smaller than those of the unamended soil HA. Application of MSWC to soil slightly reduced the metal-ion-binding capacities and affinities of soil HAs.  相似文献   

11.
Density functional theory calculations are performed to analyze the structure and stability of Cu and Cu-K clusters with 3 to 9 atoms. The results indicate that the stability of the clusters decreases after doping with a K atom. With the increase of cluster size, the stability of the clusters shows odd-even alternation. Cu8 and Cu7K clusters exhibit the highest stability. Next, different adsorption sites are considered to investigate the geometry of CunNO and Cun−1KNO clusters. By calculating the adsorption energy and the HOMO-LUMO energy gap, it is determined that both types of reactions are exothermic processes, indicating stable adsorption of NO. Notably, the CunK clusters are more active (stronger adsorption) for NO than the Cun clusters. The most chemically active clusters among CunNO and Cun−1KNO clusters are Cu8NO and Cu7KNO clusters. Finally, electron transfer and Mayer bond order analysis of Cu8NO and Cu7KNO clusters reveal that the N O bond order decreases due to electron transfer when Cu/Cu-K clusters adsorb NO. In this process, the N atom is the electron donor and the Cu atom is the electron acceptor. Fundamental insights obtained in this study can be useful in the design of Cu/Cu-K catalysts.  相似文献   

12.
The thermal behaviour of the complexes of N,N-diethyl-N-benzoylthiourea (DEBT) with Ni(II), Cu(II), Pt(II), Pd(II) and Ru(III) was studied using differential thermal analysis (DTA) and thermogravimetry (TG). These complexes undergo only a pyrolytic decomposition process. A gas chromatography-mass spectrometry combined system was used for the verification of the first decomposition product and X-ray diffraction method for the characterization of the final products of pyrolysis.This work was partially supported by Erciyes University Fund Project (AFP 94).  相似文献   

13.
The reactions of high-molecular-weight polydimethylsilane with metal chlorides in variable oxidation states at high temperature in the absence of a solvent afford mixtures of ,-dichloropermethyloligosilanes Cl(Me2Si) m Cl (m= 2—9). The influence of the reaction conditions (temperature, reaction time, and the reagent ratio) on the composition and yields of the reaction products was examined.  相似文献   

14.
《Polyhedron》1999,18(8-9):1303-1310
The syntheses and structures of four homoleptic metal–metal triply-bonded M2R6 compounds [Mo2(CH2CMe2Ph)6, 1; Mo2(CH2SiMe2Ph)6, 2; W2(CH2SiMe2Ph)6, 3; and W2(CH2Ph)6, 4] are reported. The synthetic effort suggests that ditungsten compounds are inherently more difficult to prepare and more thermally sensitive than dimolybdenum compounds, probably as a result of the larger dimetal core the ligands must protect. The structural data confirm that dimetal hexaalkyls exhibit shorter M≡M distances than do dimetal hexaalkoxides, even in a matched pair case where steric differences are minimal.  相似文献   

15.
 The spectroscopic properties of M–SiO and M–(SiO)2 (1–1 and 1–2 complexes with M = Cu, Ag, or Au) have been theoretically studied. It has been shown that both M–SiO and M–(SiO)2 compounds in their ground state are bent with a metal–Si bonded structure. The calculated M(ns) spin density agrees well with the electron spin resonance experimental data. From a topological analysis, it has been shown that a rather large charge transfer occurs from the metal towards the SiO moiety, and that the M–Si bond energy correlates with the electron density located at the M–Si bond path (bond critical point). Received: 6 July 2000 / Accepted: 11 October 2000 / Published online: 19 January 2001  相似文献   

16.
The chemical mechanism of Normal Raman Scattering (NRS) and pre-surface enhanced Raman scattering (pre-SERS) spectra for Pyrazine–Ag2 complex, Ag2–Pyrazine–Ag2 junction and Ag2–Pyrazine–Au2 junction were investigated with density functional theory (DFT) and charge difference densities (CDDs) for the first time. The NRS intensities of the above three structures enhanced obviously relative to isolated Pyrazine and the enhancement mechanism was confirmed to be static chemical enhancement. The pre-SERS intensities of the above three structures enhanced evidently compared to corresponding NRS intensities, and the enhancement mechanism was confirmed to charge transfer (CT) resonance Raman enhancement. The largest enhanced orders of NRS and pre-SERS intensities among the three structures were up to 103 and 105, respectively. Compared the intensity of pre-SERS with corresponding intensity of NRS spectra, the enhancement effect of Pyrazine–Ag2 complex was larger than the others. Intramolecular and intermolecular CT on resonant electronic transition were described by CDDs.  相似文献   

17.
Capillary electrophoresis (CE) has been applied to metal-ion analysis during the last 10 years. To improve sensitivity and selectivity different modes of detection have been adapted or developed. The selection of commercially available detection systems for metal-ion analysis is still primarily limited to UV–Vis detection, although other commercial systems, e.g. fluorescence, conductivity, or interfaces for coupling to mass spectrometry (MS) or inductively coupled plasma mass spectrometry (ICP–MS) are becoming available. High demands are made on any detector used in CE, because the analytical signal has to be extracted from less than 1 nL of sample, which corresponds to a total amount of ≤ 10–12 to 10–15 mol analyte. This paper compares currently available and recently developed detection methods for CE as applied to the analysis of metal ions. Commercially available techniques, for example UV– Vis, fluorescence, or mass spectrometry, and other new detection methods including electrochemistry, radioactivity, and XRF, are discussed and future trends are anticipated.  相似文献   

18.
Four metal complexes based on the phenyl-bridged pyridine ligand with tetrathiafulvalene unit (TTF-Ph-Py, L), NiII(acac)2(L)2 (1, acac = acetylacetonate), M(hfac)2(L)2 (M = NiII, 2; M = CuII, 3; hfac = hexafluoroacetylacetonato) and [CoII(TpPh2)(OAc)(L)]·H2O (4, TpPh2 = hydridotri(3,5-diphenylpyrazol-1-yl) borate), have been synthesized and structurally characterized. The absorption spectra and redox behaviors of these new compounds have been studied. Optimized conformation and molecular orbital diagram of L has been calculated with density functional theory (DFT).  相似文献   

19.
Three barbital-based alkaline earth metal complexes, [Ca(Barb)2]?·?3H2O (1), [Ba2H(Barb)5] (2) and [Mg(Barb)2]?·?2H2O (3) (Barb?=?5,5-diethyl barbiturate sodium salt), were synthesized and characterized with elemental analysis, thermal analysis, and infrared, Raman, ultraviolet, and NMR (1H and 13C) spectroscopies. Single-crystal X-ray diffraction studies reveal that 2 is a dimer. Each barium(II) is surrounded by an O7N2 donor set in an approximate monocapped square antiprism with Ba–O distances ranging from 2.6512(14) to 2.9168(15)?Å and Ba–N distances of 2.7601(15) and 3.2558(17)?Å. The complex forms polymeric networks in the solid state with different coordinating abilities of O and N donors and N–H···O hydrogen bonds. The antimicrobial activities of 13 were observed against different gram-positive and gram-negative bacteria, yeast, and molds. Variable antimicrobial activity against the different bacteria strains was observed and compared with that of standard antibiotics; minimum inhibitory concentration values ranged from 22 to 170?µg?mL?1 for bacteria.  相似文献   

20.
In this review are classified and analyzed structural parameters of almost 90 monomeric organoplatinum complexes with inner coordination spheres consisting of PtPCOX (X?=?N, Cl, S), PtPCNX (X?=?Cl, S, Br, I, As) and PtPCClX (X?=?S, I, As). These complexes crystallized in three crystal systems: orthorhombic (× 11), triclinic (× 32) and monoclinic (× 45). Distorted square planar arrangements about the Pt(II) atoms are provided by mono-, heterobi- and heterotridentate donor ligands. The chelating ligands create a wide variety of four-, five- and six-membered metallocyclic rings and the effects of both steric and electronic factors influence the L–Pt–L bite angles. There are wide variations in the trans-positions of the donor ligands. Two examples are classified as distortion isomers.  相似文献   

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