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101.
A new N-TEMPO-3,5-di-tert-butylsalicylaldimine radical (1) has been synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR, UV–vis, and EPR spectroscopy and temperature dependent magnetic susceptibility. X-ray diffraction revealed that H-atoms of γ-CH in TEMPO and CH3 in salicylaldimine moieties, are located in close contact with the neighboring N–O radical group in crystal 1. The temperature dependence of the magnetic susceptibility (χm) of 1 has been fitted by the Curie–Weiss law with θ = −0.3 K within 10–300 K, suggesting the presence of a weak intermolecular antiferromagnetic interaction between radical centers at T < 10 K. It has been demonstrated that radical 1 possesses crystal structure involving co-existence of antiferromagnetic and ferromagnetic interactions through C–H?O–N contacts of γ-CH and tBu groups hydrogen atoms, in which the former path dominates over the latter. 相似文献
102.
Ataç A Yurdakul Ş Berber S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):684-689
We report synthesis of six new bis-nicotinamide metal(II) dihalide complexes [M(nia)(2)Cl(2); M = Mn, Co; nia:nicotinamide, M(nia)(2)Br(2); M = Mn, Hg; M(nia)(2)I(2); M = Cd, Cu], and their characterization by combining infrared spectroscopy with density functional theory (DFT) calculations. Infrared spectra indicate that ring-nitrogen is the active donor cite, and the atomic structure of the complexes is determined to be polymeric octahedral or distorted polymeric octahedral. Spin polarized electronic ground state is obtained for Mn, Co, and Cu halide complexes. The colors of the complexes also support the conclusion of octahedral coordination around the metal atoms, in agreement with DFT results. 相似文献
103.
Tokatlı A Ozen E Ucun F Bahçeli S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(3):1201-1211
The optimized molecular geometry, vibrational frequencies, and gauge including atomic orbital (GIAO) (1)H and (13)C NMR shift values of 5-(4-bromophenylamino)-2-methylsulfanylmethyl-2H-1,2,3-triazol-4-carboxylic acid ethyl ester have been calculated by using Hartree-Fock (HF) and density functional method (DFT/B3LYP) with 6-31G(d), 6-31G(d,p) and LANL2DZ basis sets. The optimized molecular geometric parameters were presented and compared with the data obtained from X-ray diffraction. In order to fit the calculated harmonic wavenumbers to the experimentally observed ones, scaled quantum mechanics force field (SQM FF) methodology was proceeded. Correlation factors between the experimental and calculated (1)H chemical shift values of the title compound in vacuum and in CHCl(3) solution by using the conductor-like screening continuum solvation model (COSMO) were reported. The calculated results showed that the optimized geometry well reproduces the crystal structure. The theoretical vibrational frequencies and chemical shifts are in very good agreement with the experimental data. In solvent media the energetic behavior of the title compound was also examined by using the B3LYP method with the 6-31G(d) basis set, applying the COSMO model. The obtained results indicated that the total energy of the title compound decreases with increasing polarity of the solvent. Furthermore, molecular electrostatic potential (MEP), natural bond orbital (NBO) and frontier molecular orbitals (FMOs) of the title compound were performed by the B3LYP/LANL2DZ method, and also thermodynamic parameters for the title compound were calculated at all the HF and B3LYP levels. 相似文献
104.
105.
A visco-elastoplastic model for the impact between a compact body and a composite target is presented. The model is a combination
of a nonlinear contact law that includes energy loss due to plastic deformation and a viscous element that accounts for energy
losses due to wave propagation and/or damping. The governing nonlinear equations are solved numerically to obtain the response.
A piecewise linear version of the model is also presented, which facilitates analytical solution. The model predictions are
compared to those of the well-known and commonly used Hunt–Crossley model. The effects of the various impact parameters, such
as impactor mass, velocity, plasticity, and damping, on the impact response and coefficient of restitution are investigated.
The model appears to be suitable for a wide range of impact situations, with parameters that are well defined and easily calculated
or measured. Furthermore, the resulting coefficient of restitution is shown to be a function of impact velocity and damping,
as confirmed by published experimental data. 相似文献
106.
Sema Özturk Şamil Işik Erbil Aguar Selami Şalsmaz H. K. Fun Ahmet Erdönmez 《光谱学快报》2013,46(2):245-254
Abstract The crystal structure of the title compound, C41 H35 N7 O6 S3 was determined as monoclinic by single crystal X-Ray diffraction technique. The molecular structure was identified by IR, 1H-NMR, 13C-NMR and elemental analysis. The crystal parameters of this compound are as follows: monoclinic P 2 1/n, a = 12.694(2) Å, b = 26.204(2) Å, c = 13.005(2) Å, β = 102.95(2)°, V = 4216.02(1) Å.3, Z = 4, Dx = 1.289 g/cm3, F(000) = 1704, λ (MoKα) = 0.71070 Å, μ = 0.2 mm?1. The structure was solved by SHELXS-97 and refined by SHELXL-97. R = 0.06 for 3178 observed reflections with I > 2σ (I). 相似文献
107.
Six new, sterically demanding bis(benzimidazolium) salts (2a–f) as NHC precursors have been synthesized and characterized. These salts, in combination with palladium acetate, provide active catalysts for the cross‐coupling of aryl chlorides and bromides under mild conditions in aqueous media. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
108.
109.
The in situ prepared three‐component system Pd(OAc)2–1,3‐dialkylbenzimidazolium chlorides ( 2a – f ) and Cs2CO3 catalyses, quantitatively, the Suzuki cross‐coupling of deactivated aryl chlorides and Heck coupling reactions of aryl bromide and iodide substrates. The 1,3‐dialkylbenzimidazolium salts ( 2a – f ) were characterized by conventional spectroscopic methods and elemental analysis. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
110.
A. Schenck A. Amato F.N. Gygax M. Pinkpank P. Ahmet M. Ablitz R. Settai Y. Ōnuki 《Hyperfine Interactions》1997,104(1-4):105-111
We report on ZF and TF‐studies of PrCu2 above the induced Jahn–Teller transition at 7.3 K. Generally a two‐component signal is found, one showing inhomogeneous the
other one homogeneous, temperature dependent line broadening. In ZF the former component is well represented by a Gaussian
Kubo–Toyabe function with \varDelta \simeq 6.5\,μs-1 at 7.5 K, corresponding to a field width of 76 G. This is about 30 times larger than what is calculated to arise from the
141Pr‐nuclear dipole moments alone, pointing to strong hyperfine enhanced features. TF‐field scans at 12 K revealed that the
enhancement is suppressed in external fields exceeding 1 kG. In parallel the Knight shift drops from very large values well
above 10% at 100 G to shifts of the order of 1% above 1 kG. A scaling of the Knight shifts with the corresponding relaxation
rates seems to imply that the strange field dependence below 1 kG is associated with the magnetic susceptibility of the muons’s
nearest neighbour Pr3+‐ions, a result for which we have no explanation yet to offer.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献