共查询到20条相似文献,搜索用时 15 毫秒
1.
Zhong-Lin Lu Xiao-Sheng Yang Rui-Yao Wang Hoong-Kun Fun Suchada Chantrapromma 《Polyhedron》2009,28(13):2565-2570
Three pyridine coordinated cyclopalladated complexes: (S)-chloro{2-[2-(4-tert-butyl)oxazolinyl]phenyl-C,N}(4-R-pyridine)palladium(II) (R = H, 2; R = CF3, 3; R = NMe2, 4), have been synthesized and structurally characterized. While the crystal structure shows that 2 has a normal N,N-trans-conformation in the coordination sphere of palladium(II), 3 and 4 exhibit uncommon N,N-cis-conformations. From 1H NMR measurements, the major coordination isomer in deuterated chloroform solution is N,N-trans configuration for three palladacycles. It was found that the three complexes catalyze effectively the methanolysis of the PS pesticides including chiral thiophosphates but show different activity depending on the substituents of co-coordinated pyridine ring in 2–4. 相似文献
2.
NIR-FT Raman and FT-IR spectra of the crystallized biologically active molecule N,N′-diphenylguanidinium nitrate (DGN) have been recorded and analyzed using quantum chemical computations based on density functional theory. The extraordinary basicity and strong stability of this novel bioactive compound has been discussed as the consequence of resonance stabilization leading to Y-aromaticity and hydrogen bonding. This peculiar Y-delocalization character of DGN is well reflected in the optimized geometry and bond order (BO) calculations. The observance of the equality of C–N bond lengths in the protonated species indicates delocalization of the π-electron system. The spectroscopic and natural bonds orbital (NBO) analysis confirms the occurrence of strong network of inter molecular hydrogen bonds. The changes in electron density in the global minimum and in the energy of hyperconjugative interactions of DGN calculated by second order perturbation theory have been studied extensively in comparison with the values of the neutral species. The observed characteristic ring vibrations are well fit with the theoretical values calculated at B3LYP/6-31G* level. 相似文献
3.
Rodrigo A. de Souza Antonio E. Mauro Adelino V. G. Netto Gislaine A. da Cunha Eduardo T. de Almeida 《Journal of Thermal Analysis and Calorimetry》2011,106(2):375-378
Palladium(II) coordination compounds of general formula trans-[PdX2(isn)2], X = Cl− (1), N3
− (2), SCN− (3), NCO− (4), isn = isonicotinamide; were synthesized and characterized in solid state by elemental analysis, infrared spectroscopy,
and simultaneous TG–DTA. TG experiments reveal that the compounds 1–4 undergo thermal decomposition in three or four stages, yielding Pd0 as final residue, according to calculus and identification by X-ray powder diffraction. 相似文献
4.
Hongwei Qiao Helin Luan Zhiming Zhou Lixue Bi Wen Yao Jimei Li Chang Chen 《Journal of Molecular Structure》2008,885(1-3):89-96
Solvation and association interactions in solutions of LiBF4/DMCC (DMCC for N,N-dimethylcarbamoyl chloride) and LiBF4/DMCC–DME (DME for 1,2-dimethoxyethane) have been studied as a function of concentration of lithium tetrafluoroborate by infrared and Raman spectroscopy. Strong interactions between Li+ and solvent molecules or BF4− anions are observed. The apparent solvation numbers of Li+ in LiBF4/DMCC solutions were deduced. Band-fitting to the B–F stretching band of BF4− anion permits detailed assess of the ion pairing. Based on the calculations of density function theory, optimal structures of Li+(DMCC)n (n = 1–3) were suggested. It is found that the lithium ion was preferentially solvated by DME in DMCC–DME binary solvents. This finding is supported by quantum chemistry calculations. 相似文献
5.
《Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy》1977,33(12):1101-1102
The i.r. and Raman spectra (100–400 cm−1) of seven dimeric cyclopalladated compounds are reported. The metallated ligands are azobenzene, N,N-dimethyl-benzylamine, phenylhydrazone acetophenone, N-phenyl, N-methyl hydrazone acetophenone, N-benzylacetophenone imide, benzo(h)quinoline and 8-methylquinoline. The spectral changes taking place on substitution of the Cl by Br, enabled the assignment of the bridged metal—Cl and Br frequencies, in this type of complex. 相似文献
6.
Floris P. J. T. Rutjes Henk Hiemstra Hendrik H. Mooiweer W. Nico Speckamp 《Tetrahedron letters》1988,29(52):6975-6978
Acid catalyzed cyclization of methoxymethyl substituted acyclic hydrazides 4 provides cyclic hydrazides 5 in moderate to good yields through the intermediacy of N,N′-di(methoxycarbonyl)hydrazinium intermediates. 相似文献
7.
Photoinduced electron transfer reactions of several electron-deficient olefins with N,N,N′,N′-tetramethylbenzidine (TMB) in acetonitrile solution have been studied by using laser flash photolysis technique and steady-state fluorescence quenching method. Laser pulse excitation of TMB yields 3TMB* after rapid intersystem crossing from 1TMB*. The triplet which located at 480 nm is found to undergo fast quenching with the electron acceptors fumaronitrile (FN), dimethyl fumarate (DMF), diethyl fumarate (DEF), cinnamonitrile (CN), -acetoxyacrylonitrile (AAN), crotononitrile (CrN) and 3-methoxyacrylonitrile (MAN). Substituents binding to olefin molecule own different electron-donating/withdrawing powers, which determine the electron-deficient property (π-cloud density) of olefin molecule as well as control the electron transfer rate constant directly. The detection of ion radical intermediates in the photolysis reactions confirms the proposed electron transfer mechanism, as expected from thermodynamics. The quenching rate constants of triplet TMB by these olefins have been determined at 510 nm to avoid the disturbance of formed TMB cation radical around 475 nm. All the values approach or reach to the diffusion-controlled limit. In addition, fluorescence quenching rate constants have been also obtained by calculating with Stern–Volmer equation. A correlation between experimental electron transfer rate constants and free energy changes has been explained by Marcus theory of adiabatic outer-sphere electron transfer. Disharmonic kq values for CN and CrN in endergonic region may be the disturbance of exciplexs formation. 相似文献
8.
Peter Rapta Andrea Vargov Júlia Polovkov Anton Gatial Ladislav Omelka Petr Majzlík Martin Breza 《Polymer Degradation and Stability》2009,94(9):1457-1466
Electrochemical and spectroscopic (EPR, UV–Vis, IR) studies of the aromatic secondary amines N,N′-diphenyl-1,4-phenylenediamine (DPPD), N-phenyl-N′-isopropyl-p-phenylene diamine (IPPD), N-phenyl-N′-(α-methylbenzyl)-p-phenylenediamine (SPPD) and N-phenyl-N′-(1,3-dimethyl-butyl)-p-phenylenediamine (6PPD), which represent the most important group of antioxidants used in the rubber industry, are presented. During oxidation, all the compounds show reversible redox couples in acetonitrile/0.1 M TBABF4. The first oxidation potential depends substantially on the R substituent at the –N′H– moiety. Very similar UV–VIS spectra of monocation radicals and dications for all the compounds were observed by applying anodic oxidation as well as oxidation by tert-butyl hydroperoxide both in air and in inert atmosphere. The samples with N′-bonded aliphatic carbon in the molecule (e.g. IPPD) heated in air undergo consecutive chemical reactions leading to the formation of –N′C– group. By the use of RO2 radicals only very low concentration of nitroxide radicals was obtained. Very high concentration of nitroxide radicals was achieved using 3-chloroperbenzoic acid. In the oxidation of investigated aromatic secondary amines with powder PbO2 no EPR spectra were observed and UV–Vis and IR studies indicate the rapid formation of the final dehydrogenated oxidation product. 相似文献
9.
Hüseyin Ünver Ayhan Elmali Asl Karaka Hülya Kara Emine Donmez 《Journal of Molecular Structure》2006,800(1-3):18-22
A Schiff base complex N,N′-bis(2-hydroxy-1-naphthylmethylidene)-1-methyl-1,2- diaminoethane-N,N′,O,O′-nickel(II) has been synthesized. The title compound has been characterized by FT-IR and UV–vis spectroscopies. The UV–vis experiments indicate that the compound has solvatochromism in the UV region, implying non-zero molecular first hyperpolarizability. To investigate microscopic second-order nonlinear optical (NLO) behavior of the examined complex, the electric dipole moments (μ) and the first static hyperpolarizabilities (β) were computed using Finite Field second-order Møller Plesset (FF MP2) perturbation procedure. According to ab initio quantum mechanical calculations, the title complex exhibits non-zero β values, revealing microscopic second-order NLO behavior. 相似文献
10.
Muhammad Haleem Khan Syed Manzoor Hussain Bukhari Akbar Ali Khurram Liaqat Srosh Fazal 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(1):113-119
A simple, sensitive and efficient spectrophotometric method is proposed for rapid determination of uranium using arsenazo-III
in perchloric acid. The reaction between arsenazo-III and U(VI) was instantaneous in 3 mol L−1 HClO4.
N-cetyl-N,N,N-trimethylammonium bromide was used for increasing the sensitivity and selectivity of the complex. The absorbance remains
stable for over 48 h in the presence of surfactant. The method allows the determination of uranium in the range of 1–20 μg g−1 with a molar absorptivity of 3.9 × 105 dm3 mol−1 cm−1 at 681 nm. Sandell’s sensitivity of the complex was calculated to be 6.4 ng cm−2 at λmax 681 nm. A significant enhancement was achieved in the sensitivity of the proposed method whereas, Relative Standard Deviation
was reduced from 4.5 to 1.7% in the presence of surfactant. Among various diverse ions studied, fluoride, cyanide, citrate,
sulfate and phosphate interfere beyond the tolerance limit. Among cations only Cr3+ and Co2+ decreased the normal absorbance. The validity of the reported method was tested by determining uranium in the environmental
water samples and Standard Reference Material. The results agreed closely with the reported values. The proposed method is
new, easy in operation and better in sensitivity than many of the existing methods. 相似文献
11.
12.
Samuel P. Kusumocahyo Kimio Sumaru Takashi Iwatsubo Toshio Shinbo Toshiyuki Kanamori Hideto Matsuyama Masaaki Teramoto 《Journal of membrane science》2006,280(1-2):73-81
The facilitated transport mechanism of cerium(III) ions through polymer inclusion membrane (PIM) consisting of cellulose triacetate (CTA) as a polymer matrix, 2-nitrophenyl n-octyl ether (NPOE) as a solvent and N,N,N′,N′-tetraoctyl-3-oxapentanediamide (TODGA) as a carrier was studied. In order to evaluate the mass transport phenomena in the PIM, a mathematical model was derived from the Fick's first law and the equations for the extraction and the material balance. Methods to determine the values of the transport parameters such as the diffusion coefficient are described, and the dependency of the flux on the experimental condition was calculated. The model is very useful as a design tool to analyze and optimize the concentration process of low level radioactive wastewater using the PIM. 相似文献
13.
14.
Milutin M. Milosavljevi? Aleksandar D. Marinkovi? Vlada B. Veljkovi? Dragan D. Milenkovi? 《Monatshefte für Chemie / Chemical Monthly》2012,13(2):43-49
Abstract
The kinetics of the syntheses of N-alkyl, N,N-dialkyl, and N-(4-substituted phenyl) O-ethyl thioncarbamates from sodium ethyl xanthogenacetate, ten alkylamines, and eight substituted anilines were studied at 25, 30, 35, and 40 °C. The reactions were found to follow second-order kinetics. The kinetic (Arrhenius) parameters, such as the activation energy and the frequency factor, as well as the Eyring parameters, such as the standard entropy, the standard Gibbs energy, and the standard enthalpy of activation, were calculated from the second-order rate constants. The mechanism of the reaction was postulated based on the kinetic studies presented and the optimization of the reaction mechanism using the MOPAC PM6 semi-empirical method. 相似文献15.
Solid complexes of lighter lanthanide nitrates with N,N′-dinaphthyl-N,N′-diphenyl-3,6-dioxaoctanediamide (DDD), Ln(NO3)3(DDD) (Ln = La---Nd, Sm) have been prepared in non-aqueous media. These complexes have been characterized by elemental analysis, conductivity measurements, IR spectra, electronic spectra and TG-DTA techniques. In all the complexes, DDD and NO3− are coordinated to the lanthanide ions as tetradentate and bidentate ligands, respectively. The differences in the IR and electronic spectra between these complexes and lanthanide nitrate complexes with N,N,N′,N′-tetraphenyl-3,6-dioxaoctanediamide (TDD) are discussed. 相似文献
16.
Pierre Thury Martine Nierlich Marie-Christine Charbonnel Christophe Den Auwer Jean-Pierre Dognon 《Polyhedron》1999,18(27):3620-3603
A monoclinic form of the complex between lanthanum(III) nitrate and tetraethylmalonamide (TEMA), La(NO3)3(TEMA)2, 1, differing from the triclinic form 2 previously reported, is described. 1 undergoes an evolution with time which leads to the form 2, which in its turn undergoes a temperature-driven phase transition previously unreported, leading to the formation of 3. 相似文献
17.
N-(β-Hydroxy)amides can be cyclised by reaction with diisopropylcarbodiimide (DIC) to give the corresponding 2-oxazolines in high yields. The reaction requires only very mild Lewis-acid catalysis (5 mol % Cu(OTf)2) and can be accomplished with simple heating, or in very short reaction times under microwave irradiation. 相似文献
18.
19.
The first N-containing trifluorovinyl ether monomer (CF3)2NCF2OCFCF2 was synthesized. The starting perfluoroalkyl imine CF3–NCF2 was converted to the perfluoroalkyl amine (CF3)2NH by HF. The amine was converted into the carbamoyl fluoride (CF3)2NC(O)F via reaction with carbonyl fluoride COF2 in the presence of NaF. The carbamoyl fluoride was subjected to catalytic fluorination with molecular F2 in the presence of CsF to afford the hypofluorite (CF3)2NCF2(OF). The hypofluorite was added to CFClCFCl to provide a saturated halocarbon ether. Dechlorination of the ether with zinc in DMSO resulted in the title monomer. The new vinyl ether monomer readily copolymerizes with TFE. 相似文献
20.
Mohamed El-Sayed Hardy Müller Gerd Rheinwald Heinrich Lang Stefan Spange 《Monatshefte für Chemie / Chemical Monthly》2003,50(11):361-370
N-(2′-Hydroxy-4′-N,N-dimethylaminobenzylidene)-4-nitroaniline [HDBN] has been used as a model for investigating intra- and intermolecular D–A (donor–acceptor) interactions in various environments
by means of UV/Vis spectroscopy. UV/Vis spectra of HDBN have been measured in various solvents, ethanolic solutions of different pH, adsorbed on silica, and in the solid state. A bathochromic shift of νmax is observed with increasing the dipolarity/polarizability and HBD (hydrogen bond donor) capacity of the solvent, which is
described by means of a multiple LSE (linear solvation energy) relationship in terms of the empirical Kamlet-Taft solvent polarity parameters. The adsorption of HDBN on Aerosil? 300-silica particles in non-HBA (hydrogen bond acceptor) solvents is explained in the same sense. Mobile protons and sol–gel
entrapping cause a hypsochromic shift due to protonation of the lone electron pair of the 4′-N,N-dimethylamino group. Hydroxide ions attack the 2′-hydroxy group which causes a bathochromic shift. A strong intramolecular
hydrogen bond between the 2′-hydroxyl hydrogen and the imine nitrogen atom is present in the solid-state structure causing
an unprecedented bathochromic shift. 相似文献