Berechnung der 19F- und 195 Pt-NMR-Verschiebungen von FIuoro-Chloro-Bromo-Platinaten(IV) / Calculation of 19F and 195Pt NMR Shifts of Fluoro-Chloro-Brom o-Platinates(IV )

1997 ◽  
Vol 52 (4) ◽  
pp. 435-442 ◽  
Author(s):  
H.-H. Drews ◽  
W. Preetz
Keyword(s):  
Experimental Data ◽  
Chemical Shifts ◽  
Coupling Constant ◽  
Lower Field ◽  
Trans Influence ◽  
Nmr Signals ◽  
Increments Of Chemical Shifts ◽  
Good Agreement

By reaction of [PtBr4]2- with XeF2 in dichloromethane product mixtures containing nine fluoro-chloro-, four fluoro-bromo- and 15 fluoro-chloro-bromo-platinates(IV) are formed. All complexes are detectable by in situ l9F NMR measurements. Due to the increasing trans influence F < Cl < Br, the signals <5(19F) of symmetric F-Pt-F axes observed at highest field are shifted downfield on the average by 93 ppm as compared with δ(19F•) of F••Pt-Cl′ axes, and further to lower field by 40 ppm for <5(F••) of F••-Pt-Br″ axes. For the same reason the coupling constant 1J(F••Pt) ≈ 1099 Hz is by 13.3 % smaller than 1J(F•Pt) ≈ 1268 Hz, which is by 32.3 % smaller than δ(FPt) ≈ 1873 Hz. Based on the axis method, and taking into account characteristic increments of chemical shifts depending on cis influences, the calculation of the 195Pt NMR signals of 27 observed species of the system [PtFnCl6-n-mBrm]2- n, m = 0 - 6, has been successful. The 195Pt NMR shifts of further 29 so far not detected complexes are predicted. Using parameters depending on the geometry of the complex, the 19F NMR shifts of 28 F-containing platinates(IV) have been calculated in good agreement with the experimental data. 19F resonances are predicted for 19 so far missing complexes.

APPLICATION OF A NEW HAMILTONIAN OF INTERACTION TO THREE-DIMENSIONAL STRUCTURES

2004 ◽  
Vol 18 (09) ◽  
pp. 1351-1368
Author(s):  
ANDREI DOLOCAN ◽  
VOICU OCTAVIAN DOLOCAN ◽  
VOICU DOLOCAN
Keyword(s):  
Experimental Data ◽  
Cohesive Energy ◽  
Noble Gases ◽  
Three Dimensional ◽  
The Other ◽  
Ionic Crystals ◽  
Coupling Constant ◽  
Good Agreement

Using a new Hamiltonian of interaction we have calculated the cohesive energy in three-dimensional structures. We have found the news dependences of this energy on the distance between the atoms. The obtained results are in a good agreement with experimental data in ionic, covalent and noble gases crystals. The coupling constant γ between the interacting field and the atoms is somewhat smaller than unity in ionic crystals and is some larger than unity in covalent and noble gases crystals. The formulae found by us are general and may be applied, also, to the other types of interactions, for example, gravitational interactions.

Ligand Redistribution Equilibria in Aqueous Fluoroberyllate Solutions

1998 ◽  
Vol 53 (11) ◽  
pp. 1294-1300 ◽  
Author(s):  
Michael Schmidt ◽  
Hubert Schmidbaur
Keyword(s):  
Experimental Data ◽  
Ligand Exchange ◽  
Room Temperature ◽  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Individual Species ◽  
Ph Values ◽  
Exchange Processes ◽  
The Individual ◽  
Good Agreement

The composition of aqueous fluoroberyllate solutions has been studied by 9Be and 19F NMR spectroscopy for various ratios of the beryllium and fluorine concentrations, and at different pH values. The equilibrium constants have been determined for the ligand exchange processes, which involve the species [Be(OH2)4]2+, [BeF(OH2)3]+, [BeF2(OH2)2], [BeF3(OH2)]- , and [BeF4]2-. These equilibria are shifted towards [BeF4]2- at high pH. No polynuclear fluoroberyllates have been detected. The fluoride exchange between the individual species is slow on the NMR time scale at room temperature, and separate sharp signals with the expected multiplicity are therefore recorded. Calculated 9Be chemical shifts are in good agreement with experimental data.

Effects of HMX Particle Size on the Shock Initiation of PBXC03 Explosive

2012 ◽  
Vol 13 (2) ◽  
Author(s):  
Li-Jing Wen ◽  
Zhuo-Ping Duan ◽  
Lian-Sheng Zhang ◽  
Zhen-Yu Zhang ◽  
Zhuo-Cheng Ou ◽  
...  
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Reaction Rate ◽  
Pressure Gauge ◽  
Rate Model ◽  
Shock Initiation ◽  
Gauge Data ◽  
Medium Formulation ◽  
Good Agreement

AbstractA series of shock initiation experiments are performed on the PBXC03 explosives in different formulations to understand the influence of the explosive particle size on the shock initiation, and the in-situ pressure gauge data are obtained which show that shock sensitivity decreases with the explosive particle size under the test condition used in this paper. Moreover, a mesoscopic reaction rate model which is calibrated by the experimental data on a medium formulation PBXC03 explosive is adopted and then applied to predict numerically the shock initiation of other PBXC03 explosives in different formulations. The numerical results are in good agreement with the experimental data.

scholarly journals Organocatalyzed Beckmann Rearrangement of Cyclohexanone Oxime by Trifluoroacetic Anhydride in a Microreactor

2021 ◽  
Author(s):  
Chencan Du ◽  
Yubin Wang ◽  
Jian Deng ◽  
Guangsheng Luo
Keyword(s):  
Experimental Data ◽  
Reaction Rate ◽  
Beckmann Rearrangement ◽  
Trifluoroacetic Anhydride ◽  
Cyclohexanone Oxime ◽  
In Situ Ftir ◽  
Equilibrium Relationship ◽  
Experimental Parameters ◽  
Good Agreement

An efficient method for the Beckmann rearrangement of cyclohexanone oxime (CHO) catalyzed by trifluoroacetic anhydride (TFAA) is proposed in this work. The effects of experimental parameters on the reaction rate are studied, including CHO concentration, TFAA/CHO ratio, temperature, and CPL concentration. The reaction rate shows a linear relationship with TFAA/CHO ratio and reduces with the increasing of CPL concentration. Based on the experimental data and the study of in-situ FTIR, a reaction mechanism is proposed and the equilibrium relationship between CPL and TFAA is established. A rate constant model is developed and is in good agreement with the experimental results. The TFAA/TFA catalytic system allows high conversion and reaction rate compared with other organic acids.

Darstellung, 19F- und 195Pt-NMR-Spektren, Schwingungsspektren und Normalkoordinatenanalyse von Fluoro-Chloro-Bromo-Platinaten(IV) / Preparation, 19F and 195Pt NMR Spectra, Vibrational Spectra and Normal Coordinate Analysis of Fluoro-Chloro-Bromo-Platinates(IV)

1996 ◽  
Vol 51 (11) ◽  
pp. 1563-1570 ◽  
Author(s):  
H.-H. Drews ◽  
W. Preetz
Keyword(s):  
Deae Cellulose ◽  
Exchange Chromatography ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Exchange Reactions ◽  
Normal Coordinate ◽  
Vibrational Coupling ◽  
Trans Influence ◽  
The Mean

By stereoselective ligand exchange reactions of [PtF5Cl]2− and cis-[PtF4Cl2]2− with Br− mixtures containing seven different fluoro-chloro-bromo- and two fluoro-bromo-platinates(IV) are formed, from which trans-Cs2[PtF4ClBr] 4t 11 and mer-Cs2[PtF3Clc 2Br] 3m2c 1 have been isolated by ion exchange chromatography on DEAE cellulose. All threefold mixed complexes could be detected by in situ 19F and 195 Pt NMR measurements. Due to the stronger trans influence of Cl in comparison with F on asymmetric F′-Pt-Cl′ axes the F atoms are deshielded and their signals δ(19F) are shifted on the average by 106 ppm to lower field as compared with δ(19F) of symmetric F-Pt-F axes. For the same reason the mean coupling constant 1J(FPt) of 1857 Hz is 44 % higher than 1J( FPt) of 1288 Hz. The substitution of a cis positioned Cl against Br causes shifts of -7,6 ppm for δ(19F) and of -8,4 ppm for δ(19F ). The cis influence on the coupling constants 1J(F P t) and 1J( FPt), on the average 4 Hz, is more than two orders of magnitude smaller than the trans influence. The coupling constants between inequivalent F atoms 2J(FF) amounts to 44 Hz. The mean highfield shift of the l95Pt signals on exchange of one F for Cl is 1177, of one Cl for Br 210 ppm. Due to the increasing trans influence F < Cl < Br on the stretching vibrations of asymmetrically coordinated axes characteristic frequency shifts of up to 15 % are observed. The normal coordinate analyses performed on 4t11 and 3m2c 1 reveal that the force constant fd(PtF) is by 15 % higher than fd(PtF), and that fd(PtCl′) is by 31 % higher than fd(PtCl). Very intense Raman bands at 277 and 267 cm −1 are explained by strong vibrational coupling of the π-deformation with a symmetric valence mode of the Cl -Pt-Br′axis.

Addition of the nitroxyl radical TEMPO to 1-naphthylketene: formation of an unusual adduct

1999 ◽  
Vol 77 (5-6) ◽  
pp. 806-809 ◽  
Author(s):  
Jennifer Carter ◽  
Michael H Fenwick ◽  
Wen-wei Huang ◽  
Vladimir V Popik ◽  
Thomas T Tidwell
Keyword(s):  
Nitroxyl Radical ◽  
Chemical Shifts ◽  
Wolff Rearrangement ◽  
Nmr Spectrum ◽  
X Ray ◽  
H Nmr ◽  
Naphthyl Ring ◽  
Nmr Signals ◽  
Very High

1-Naphthylketene (2), generated by thermal Wolff-rearrangement, is trapped in situ by 2,2,6,6-tetramethylpiridinyloxy radical (TEMPO, TO·) to form the adduct 1-naphthCH(OT)CO2T (4), whose structure is confirmed by an X-ray determination. The 1H NMR spectrum of 4 displays three CH3 groups with very high field chemical shifts (δ 0.10-0.47), and this is attributed to the location of these groups in the shielding region above the π system of the naphthyl ring. At -40°C, doubling of most of the 1H NMR signals occurs, and this is attributed to a freezing out of two conformations differing by rotation around the naphthyl—CH bond.Key words: ketene, TEMPO, restricted rotation, 1H NMR, conformational analysis, free radicals.

QCD test with the momentum spectra and the second binomial moment R2 using e+e− data

2016 ◽  
Vol 94 (9) ◽  
pp. 821-825
Author(s):  
M. Hasheminia ◽  
M.E. Zomorrodian ◽  
A. Mirjalili
Keyword(s):  
Experimental Data ◽  
Center Of Mass ◽  
Coupling Constant ◽  
Monte Carlo Data ◽  
Particle Distributions ◽  
Theoretical Approaches ◽  
A Value ◽  
Momentum Spectra ◽  
200 Gev ◽  
Good Agreement

Experimental data on the shape of hadronic momentum spectra are compared to the context of calculations in modified leading log approximation (MLLA), under the assumption of local parton hadron duality (LPHD). Considered are the inclusive momentum spectra and charged particle distributions in the reaction e+e− → hadrons, using the experimental as well as the Monte Carlo data at center of mass energies up to 200 GeV. Values of the second binomial moment R2 obtained from the multiplicity distributions are also studied. Our results are compared with both experimental data from high and low energy e+e−, e−p, and pp experiments and QCD calculations in various theoretical approaches. In general, good agreement is found between the measurements and the corresponding QCD predictions. A quantitative check of LPHD + MLLA has been performed by extracting a value of the strong coupling constant from the corresponding distributions. Possible explanations for all these features will be presented in this paper.

scholarly journals Electrochemical oxidation of ferricyanide

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mun Hon Cheah ◽  
Petko Chernev
Keyword(s):  
Experimental Data ◽  
Dft Calculations ◽  
Electrochemical Oxidation ◽  
Oxidation Product ◽  
In Situ Ftir ◽  
Stable Product ◽  
Good Agreement

AbstractWe report the electrochemical oxidation of ferricyanide, [FeIII(CN)6]3− and characterised the oxidation product by in-situ FTIR and XAS spectroelectrochemistry methods. Oxidation of [FeIII(CN)6]3− is proposed to proceed via a tentative Fe(IV) intermediate that undergoes reduction elimination to give cis-[FeIII(CN)4(CH3CN)2]1− as stable product in acetonitrile. Speciation of the oxidation product by DFT calculations is underpinned by good agreement to experimental data.

The relationship between carbon-13 substituent chemical shifts and proton coupling constants in aza-aromatic systems

1984 ◽  
Vol 37 (2) ◽  
pp. 311 ◽  
Author(s):  
IB Cook ◽  
S Pengprecha ◽  
B Ternai
Keyword(s):  
Experimental Data ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Proton Proton ◽  
Proton Coupling ◽  
Substituted Pyridines ◽  
Aromatic Systems ◽  
The Relationship

An equation which relates the ortho carbon-13 substituent chemical shift α-SCS in aza-aromatics to the ortho proton-proton coupling constant 3J(HH) in the corresponding carbocyclic compound is derived from experimental data. The implications for N-N bond fixation in diaza-aromatics are discussed. When the equation is applied to 2-substituted pyridines, an electronegativity parameter must be included to explain the results.

Calculation of 15N NMR Parameters of Azides and Some Related Compounds. Revisiting the Methylation of Nitrous Oxide N2O

2011 ◽  
Vol 66 (10) ◽  
pp. 1079-1082 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Experimental Data ◽  
Nitrous Oxide ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Experimental Conditions ◽  
Nmr Parameters ◽  
Related Compounds ◽  
Good Agreement

The results of a calculation of 15N NMR parameters (chemical shifts and coupling constants) of azides and related compounds are in reasonably good agreement with experimental data, even for triazadienyl fluoride, F-N3. The reaction between [CH3]+ and nitrous oxide, N2O, can yield either an O- or an N-methylated cation, [Me(N2O)]+. The calculated 15N NMR parameters clearly indicate that under the experimental conditions N-methylation to give [MeNNO]+ is preferred instead of the methoxydiazonium ion [MeONN]+ previously proposed.

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