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1.
Falk Ebeler Dr. Yury V. Vishnevskiy Beate Neumann Dr. Hans-Georg Stammler Priv.-Doz. Dr. Rajendra S. Ghadwal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(31):e202200739
Mesoionic dithiolates [(MIDtAr)Li(LiBr)2(THF)3] (MIDtAr={SC(NDipp)}2CAr; Dipp=2,6-iPr2C6H3; Ar=Ph 3 a , 3-MeC6H4 (3-Tol) 3 b , 4-Me2NC6H4 (DMP) 3 c ) and [(MIDtPh)Li(THF)2] ( 4 ) are readily accessible (in≥90 % yields) as crystalline solids on treatments of anionic dicarbenes Li(ADCAr) ( 2 a - c ) (ADCAr={C(NDipp)2}2CAr) with elemental sulfur. 3 a - c and 4 are monoanionic ditopic ligands with both the sulfur atoms formally negatively charged, while the 1,3-imidazole unit bears a formal positive charge. Treatment of 4 with (L)GeCl2 (L=1,4-dioxane) affords the germylene (MIDtPh)GeCl ( 5 ) featuring a three-coordinated Ge atom. 5 reacts with (L)GeCl2 to give the Ge−Ge catenation product (MIDtPh)GeGeCl3 ( 6 ). KC8 reduction of 5 yields the homoleptic germylene (MIDtPh)2Ge ( 7 ). Compounds 3 a - c and 4 – 7 have been characterized by spectroscopic studies and single-crystal X-ray diffraction. The electronic structures of 4 – 7 have been analyzed by DFT calculations. 相似文献
2.
The main mechanisms of leakage currents in thin lead zirconate titanate (PZT) ferroelectric films prepared by the sol–gel method are discussed. Four specific regions are determined in I–V dependencies. At very weak fields (10–20 kV/cm), the current falls with the voltage increase as a result of depolarization. In the low fields region (about 70–100 kV/cm), the leakage current decreases with the decrease of voltage ramp speed and its components are the ohmic and displacement currents. In the high fields region (≥130 kV/cm), the leakage current increases with the decrease of step voltage ramp in contrast to the previous case. Possible conductivity mechanisms are the Poole– Frenkel emission and hopping conduction. In the transition region between above-mentioned ones (from 80–90 to ~130 kV/cm), an abrupt unstable increase of current is observed caused by breakdown of reverse bias Schottky barrier. Depolarization currents are studied for sol–gel PZT films prepared at different preparation conditions. 相似文献
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4.
Yuri V. Vishnevskiy Natalja Vogt Vitaliy I. Korepanov Arkadii A. Ivanov Lev V. Vilkov Vladimir V. Kuznetsov Nina N. Mahova 《Structural chemistry》2009,20(3):435-442
The molecular structure of N-chlorosuccinimide has been studied by GED method at the nozzle temperature of 116 °C. Vibrational corrections to the r
a parameters, Δ(r
a − r
e), have been calculated using the scaled quadratic and cubic force constants from B3LYP/6-31G(df,p) calculations. The force
field scaling has been carried out using the IR and Raman spectra of the solid N-chlorosuccinimide. The molecular skeleton and the bond conformation around nitrogen were found to be planar within large experimental
errors. The equilibrium geometrical parameters derived from the experimental data assuming C
2v
molecular symmetry and those from MP2(fc)/6-311G(3df,2pd) calculations are in a good agreement. 相似文献
5.
NL Asfandiarov AI Fokin VG Lukin EP Nafikova GS Lomakin VS Fal'ko YV Chizhov 《Rapid communications in mass spectrometry : RCM》1999,13(12):1116-1123
A series of anthraquinone (C(14)O(2)H(8)) derivatives has been studied by means of electron capture negative ion mass spectrometry (ECNI-MS), photoelectron spectroscopy (PES), and AM1 quantum chemical calculations. Mean lifetimes of molecular negative ions M(-.) (MNI) have been measured. The mechanism of long-lived MNI formation in the epithermal energy region of incident electrons has been investigated. A simple model of a molecule (a spherical potential well with the repulsive centrifugal term) has been applied for the analysis of the energy dependence of cross sections at the first stage of the electron capture process. It has been shown that a temporary resonance of MNI at the energy approximately 0.5 eV corresponds to a shape resonance with lifetime 1-2.10(-13) s in the f-partial wave (l = 3) of the incident electron. The next resonant state of MNI at the energy approximately 1.7 eV has been associated with the electron excited Feshbach resonance (whose parent state is a triplet npi* transition). In all cases the initial electron state of the MNI relaxes into the ground state by means of a radiationless transition, and the final state of the MNI is a nuclear excited resonance with a lifetime measurable on the mass spectrometry timescale. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
6.
Daniel Winkelhaus Beate Neumann Dr. Hans‐Georg Stammler Dr. Raphael J. F. Berger Dr. Yuri V. Vishnevskiy Prof. Dr. Norbert W. Mitzel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(30):9312-9320
The reaction of (C6F5)2BH ( 1 ) with N,N‐dimethylallylamine ( 2 ), N,N‐diethylallylamine ( 3 ) and 1‐allylpiperidine ( 4 ) afforded the five‐membered ring systems (C6F5)2B(CH2)3NR2 (R=Me ( 5 ), Et ( 6 )) and (C6F5)2B(CH2)3N(CH2)5 ( 7 ) with an intramolecular dative B? N bond. A different product was obtained from the reaction of (C6F5)2BH ( 1 ) with N,N‐diisopropylallylamine ( 8 ), which afforded the seven‐membered ring system (C6F5)2B(CH2)3N(iPr)CH(Me)CH2 ( 9 ) under extrusion of dihydrogen. All compounds were characterised by elemental analysis, NMR spectroscopy and single‐crystal X‐ray diffraction experiments. Density functional theory (DFT) studies were performed to rationalise the different reaction mechanism for the formation of products 6 and 9 . The bonding situation of compound 9 was analysed in terms of its electron density topology to describe the delocalised nature of a borane– enamine adduct. 相似文献
7.
Dr. Jan Schwabedissen Timo Glodde Dr. Yury V. Vishnevskiy Dr. Hans-Georg Stammler Lukas Flierl Prof. Dr. Andreas J. Kornath Prof. Dr. Norbert W. Mitzel 《ChemistryOpen》2020,9(9):921-928
The refrigerant trans-1,3,3,3-tetrafluoropropene (HFO-1234ze) is used as a replacement for former cooling agents that have been phased-out due to their global warming potential or ozone depleting potential. Although it is used on a large scale, only a few vibrational data and no structural data of HFO-1234ze are known. We report structure determinations based on low-temperature single-crystal X-ray diffraction data as well as gas-phase diffraction data of HFO-1234ze and HFO-1234yf (2,3,3,3-tetrafluoropropene). Furthermore, vibrational spectra of HFO-1234ze in all phases are described. The results are discussed together with quantum-chemical calculations on the PBE0/cc-pVTZ level of theory. Combustion experiments of HFO-1234ze show carbonyl difluoride, carbon dioxide and hydrogen fluoride to be the main combustion products. 相似文献
8.
Natalja Vogt Yuri V. Vishnevskiy Arkadii A. Ivanov Jürgen Vogt Lev V. Vilkov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(13):2286-2292
The molecular structure of N-methylsuccinimide was studied by the GED method at a nozzle temperature of 69–73°C. Anharmonic
vibrational corrections to thermal-average r
a bond lengths, Δ(r
a − r
e), were calculated using the quadratic and cubic force constants from B3LYP/6-31G(df, p) calculations. The molecular skeleton was found to be planar within measurement errors. Some structural effects were likely
caused by the conjugation of the N atom with two C=O bonds. The equilibrium geometric parameters derived from the experimental
data and those from MP2/cc-pVTZ(seg-opt) calculations were in close agreement. 相似文献
9.
Vishnevskiy YV Vogt N Vogt J Rykov AN Kuznetsov VV Makhova NN Vilkov LV 《The journal of physical chemistry. A》2008,112(23):5243-5250
The equilibrium molecular structure and conformation of 1,5-diazabicyclo[3.1.0]hexane (DABH) has been studied by the gas-phase electron-diffraction method at 20 degrees C and quantum-chemical calculations. Three possible conformations of DABH were considered: boat, chair, and twist. According to the experimental and theoretical results, DABH exists exclusively as a boat conformation of C s symmetry at the temperature of the experiment. The MP2 calculations predict the stable chair and twist conformations to be 3.8 and 49.5 kcal mol(-1) above the boat form, respectively. The most important semi-experimental geometrical parameters of DABH (r(e), A and angle)e), deg) are (N1-N5) = 1.506(13), (N1-C6) = 1.442(2), (N1-C2) = 1.469(4), (C2-C3) = 1.524(7), (C6-N1-C2) = 114.8(8), (N5-N1-C2) = 107.7(4), (N1-C2-C3) = 106.5(9), and (C2-C3-C4) = 104.0(10). The natural bond orbital (NBO) analysis has shown that the most important stabilization factor in the boat conformation is the n(N) --> sigma*(C-C) anomeric effect. The geometry calculations and NBO analysis have been performed also for the bicyclohexane molecule. 相似文献
10.
Henric Steffenfauseweh Dr. Dennis Rottschäfer Dr. Yury V. Vishnevskiy Beate Neumann Dr. Hans-Georg Stammler Dr. Dariusz W. Szczepanik Priv.-Doz. Dr. Rajendra S. Ghadwal 《Angewandte Chemie (International ed. in English)》2023,62(19):e202216003
The first 1,4-distibabenzene-1,4-diide compound [(ADC)Sb]2 ( 5 ) based on an anionic dicarbene (ADC) (ADC=PhC{N(Dipp)C}2, Dipp=2,6-iPr2C6H3) is reported as a bordeaux-red solid. Compound 5 , featuring a central six-membered C4Sb2 ring with formally SbI atoms may be regarded as a base-stabilized cyclic bis-stibinidene in which each of the Sb atoms bears two lone-pairs of electrons. 5 undergoes 2 e-oxidation with Ph3C[B(C6F5)4] to afford [(ADC)Sb]2[B(C6F5)4]2 ( 6 ) as a brick-red solid. Each of the Sb atoms of 6 has an unpaired electron and a lone-pair. The broken-symmetry open-shell singlet diradical solution for ( 6 )2+ is calculated to be 2.13 kcal mol−1 more stable than the closed-shell singlet. The diradical character of ( 6 )2+ according to SS-CASSCF (state-specific complete active space self-consistent field) and UHF (unrestricted Hartree-Fock) methods amounts to 36 % and 39 %, respectively. Treatments of 6 with (PhE)2 yield [(ADC)Sb(EPh)]2[B(C6F5)4]2 ( 7 -E) (E=S or Se). Reaction of 5 with (cod)Mo(CO)4 affords [(ADC)Sb]2Mo(CO)4 ( 8 ). 相似文献