A tellurium-125 and tin-119 Mössbauer and nuclear magnetic resonance study of the group IV organotellurides

1986 ◽  
Vol 64 (5) ◽  
pp. 980-986 ◽  
Author(s):  
C. H. W. Jones ◽  
R. D. Sharma ◽  
S. P. Taneja
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Group Iv ◽  
Magnetic Resonance Study ◽  
Nmr Chemical Shifts ◽  
Nmr Parameters ◽  
Nmr Data ◽  
Mössbauer Data ◽  
Cyclic Compounds

The 125Te Mössbauer and nmr spectra of the compounds (R3X)2Te(R = Me, X = C, Si, Ge, and Sn; R = Ph, X = Ge and Sn), R3MTePh (R = Me, X = Si, Ge, and Sn; R = Ph, X = Ge, Sn, Pb), R2Sn(TePh)2 (R = Me and t-Bu), and the cyclic compounds (Me2SnTe)3, (Me2Sn)3Te2, and (t-Bu2SnTe)2 have been measured. The trends in the Mössbauer and nmr data are discussed. The Mössbauer quadrupole splittings increase as the nmr chemical shifts become more positive, corresponding to a decrease in the shielding at the tellurium nucleus. The 119Sn Mössbauer and nmr parameters of the compounds (R3Sn)2E andR3SnEPh (R = Me and Ph), (Me2SnE)3, (Me2Sn)2E2, (t-Bu2SnE)2, and Me2Sn(EPh)2 (E = S, Se, and Te) are discussed. The 119Sn Mössbauer quadrupole splittings are again observed to increase as the nmr chemical shifts become more positive. The 125Te and 119Sn nmr and Mössbauer data provide evidence that there is little transmission of bonding effects through the tin–tellurium bond as the chemical environment about the tin or tellurium is changed.

Antimony-121 nuclear magnetic resonance study of hexahaloantimonate anions

1981 ◽  
Vol 59 (20) ◽  
pp. 2940-2949 ◽  
Author(s):  
R. Garth Kidd ◽  
H. Garth Spinney
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectra ◽  
Central Atom ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Acetonitrile Solution ◽  
Trans Isomers ◽  
Magnetic Resonance Study ◽  
Chlorine Substitution ◽  
Nuclear Shielding

The seven hexahaloantimonate anions in the series [SbClnBr6−n]− have been prepared and their antimony-121 nmr spectra show that for [SbCl4Br2]−, [SbCl3Br3]−, and [SbCl2Br4]−, only the cis isomers are present in acetonitrile solution. The pairwise additivity model for central atom shielding has been used for configuration assignments. Models relevant to the higher incidence of cis over trans isomers are discussed. The nuclear shielding of 121Sb is the most sensitive to halogen substitution of all the elements whose halide chemical shifts have been studied. Antimony shieldings exhibit normal halogen dependence, with bromine substitution causing upfield shifts relative to chlorine substitution.

15N and 77Se Nuclear Magnetic Resonance Study of Selenium Diimides and Aminoselenanes

1993 ◽  
Vol 48 (10) ◽  
pp. 1307-1314 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Berthold Distler ◽  
Silke Gerstmann ◽  
Max Herberhold
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Nmr Spectra ◽  
Decomposition Product ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Magnetic Resonance Study ◽  
Nmr Data ◽  
Cp Mas Nmr ◽  
Membered Heterocycle

Selenium diimides R(NSeN)R [R = tBu (1a), tOct (1b)], the eight-membered heterocycle tBuN(SeSeSe)2NtBu (2) and the aminoselenanes of the type [R(Cl3Si)N]2Se (4a,b) and [(Me3Si)2N]2Se (5) were studied by multinuclear NMR with emphasis on 15N NMR for detection of coupling constants J(77Se15N). The selenium diimides possess the largest values of 1J(77Se15N) observed so far (1a: 158.4 and 163.5 Hz; 1 b: 158.6 and 162.8 Hz). Compound 1 b was found to be much more stable than 1a, the heterocycle 2 being the major decomposition product of 1a. The selenium diimides (1a,b) react readily with hexachlorodisilane to give the bis[alkyl(trichlorosilyl)amino]selenanes 4a,b. The solid state 13C, 15N, 29Si and 77Se CP/MAS NMR spectra of bis[bis(trimethylsilyl)amino]selenane (5) gave results in accord with the known crystal structure, and there is agreement with the solution state NMR data

Identification of acyl groups occurring in sesquiterpene lactones: Proton and carbon-13 NMR study

1987 ◽  
Vol 52 (2) ◽  
pp. 453-475 ◽  
Author(s):  
Miloš Buděšínský ◽  
David Šaman
Keyword(s):  
Chemical Shifts ◽  
Sesquiterpene Lactones ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Nmr Parameters ◽  
Nmr Data ◽  
Nmr Study ◽  
C Nmr

Characteristic 1H NMR parameters of 88 acyl groups, hitherto found as ester substituents in natural sesquiterpenic lactones, were determined from the measured spectra as well as literature data. Characteristic 13C NMR chemical shifts for 45 acyl groups were obtained in the same way; for the remaining acyls with hitherto unknown 13C NMR data the values were calculated on the basis of semiempirical relationships.

scholarly journals 1H AND 13C NMR SPECTRA OF STRYCHNOS ALKALOIDS: SELECTED NMR UPDATES

2020 ◽  
Vol 1 (14) ◽  
pp. 77-94
Author(s):  
Valentin Semenov ◽  
Dmitriy Samul'cev ◽  
Leonid Krivdin
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Mean Absolute Error ◽  
Chemical Shifts ◽  
Absolute Error ◽  
1H And 13C Nmr ◽  
Nmr Chemical Shifts ◽  
13C Nmr Chemical Shifts ◽  
Nmr Data ◽  
Distinguished Group

The PBE0/pcSseg-2//pcseg-2 calculations of 1H and 13C NMR chemical shifts were performed for a classical series of 12 Strychnos alkaloids (except for the earlier studied parent strychnine), namely akuammicine, isostrychnine, rosibiline, tsilanine, spermostrychnine, diaboline, cyclostrychnine, henningsamide, strychnosilidine, strychnobrasiline, holstiine, and icajine. It was found that calculated 1H and 13C NMR chemical shifts demonstrated markedly good correlations with available experimental data characterized by a mean absolute error of 0.22 ppm for the range of 8 ppm for protons and 1.97 ppm for the range of 180 ppm for carbons. Complimentary, present results provide essential NMR update and fill a gap in the NMR data of this distinguished group of the vitally important natural products.

Difluor-bis(methylamino)-t-butyl-phosphoran Darstellung und NMR-Daten / Difluoro-bis(methylamino)-t-butyl-phosphorane Preparation and NMR Data

1984 ◽  
Vol 39 (10) ◽  
pp. 1355-1360 ◽  
Author(s):  
Gernot Heckmann ◽  
Ekkehard Fluck ◽  
Jürgen Svara
Keyword(s):  
Title Compound ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Nmr Chemical Shifts ◽  
Nmr Data

Preparation and properties of the title compound are described. It is present as a mixture of the isomers I and II. The 1H, 13C, 19F, and 31P NMR spectra are discussed in detail. For amino fluoro phosphoranes rules for the estimation of NMR chemical shifts and coupling constants are given.

A 19F nuclear magnetic resonance study of the conjugate Brönsted-Lewis superacid HSO3F-SbF5. Part 1

1999 ◽  
Vol 77 (11) ◽  
pp. 1869-1886 ◽  
Author(s):  
Dingliang Zhang ◽  
Markus Heubes ◽  
Gerhard Hägele ◽  
Friedhelm Aubke
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Formation Reaction ◽  
H Nmr ◽  
Acid Conjugate ◽  
Nmr Methods ◽  
Cis And Trans

The Brönsted-Lewis superacid HSO3F-SbF5 or "magic acid" is re-investigated by modern 19F NMR methods over a wide concentration range. The system is found to be considerably more complex than had been assumed previously. A total of 13 different anions are identified of which only five have previously been identified in magic acid. With increasing SbF5 contents the concentration of monomeric anions like [SbF6]-, [SbF5(SO3F)]-, cis- and trans-[SbF4(SO3F)2]-, and mer-[SbF3(SO3F)3]- gradually decreases. Except for [Sb2F11]-, which is present in very small concentrations only, the formation of oligomers involves exclusively μ-fluorosulfato bridges. In addition to donor (SO3F)- and acceptor (SbF5) complex formation to give [SbF5(SO3F)]- and possibly ligand redistribution, the solvolysis of SbF5 or SbF4(SO3F) in HSO3F appears to be the principal formation reaction for polyfluorosulfatofluoroantimonate(V) anions. In glass (NMR tubes) the solvolysis product HF is converted to the oxonium ion [H3O]+, which has previously been identified by 1H NMR and structurally characterized as [H3O][Sb2F11] by us.Key words: magic acid, conjugate superacid, fluorosulfuric acid, 19F NMR spectra.

scholarly journals 29Si NMR Chemical Shifts in Crystalline and Amorphous Silicon Nitrides

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1646 ◽  
Author(s):  
Ilia Ponomarev ◽  
Peter Kroll
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Density Functional ◽  
Chemical Shifts ◽  
29Si Nmr ◽  
Hydrogenated Silicon ◽  
Nmr Chemical Shifts ◽  
Nmr Data ◽  
29Si Nmr Spectra ◽  
The Impact

We investigate 29Si nuclear magnetic resonance (NMR) chemical shifts, δiso, of silicon nitride. Our goal is to relate the local structure to the NMR signal and, thus, provide the means to extract more information from the experimental 29Si NMR spectra in this family of compounds. We apply structural modeling and the gauge-included projector augmented wave (GIPAW) method within density functional theory (DFT) calculations. Our models comprise known and hypothetical crystalline Si3N4, as well as amorphous Si3N4 structures. We find good agreement with available experimental 29Si NMR data for tetrahedral Si[4] and octahedral Si[6] in crystalline Si3N4, predict the chemical shift of a trigonal-bipyramidal Si[5] to be about −120 ppm, and quantify the impact of Si-N bond lengths on 29Si δiso. We show through computations that experimental 29Si NMR data indicates that silicon dicarbodiimide, Si(NCN)2 exhibits bent Si-N-C units with angles of about 143° in its structure. A detailed investigation of amorphous silicon nitride shows that an observed peak asymmetry relates to the proximity of a fifth N neighbor in non-bonding distance between 2.5 and 2.8 Å to Si. We reveal the impact of both Si-N(H)-Si bond angle and Si-N bond length on 29Si δiso in hydrogenated silicon nitride structure, silicon diimide Si(NH)2.

A carbon-13 nuclear magnetic resonance study of the basicities of aliphatic alcohols

1987 ◽  
Vol 65 (8) ◽  
pp. 1769-1774 ◽  
Author(s):  
Donald G. Lee ◽  
Kenneth J. Demchuk
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Free Energy ◽  
Hydrogen Bonding ◽  
Chemical Shifts ◽  
Intramolecular Hydrogen Bonding ◽  
Nuclear Magnetic Resonance Study ◽  
Slope Parameter ◽  
Magnetic Resonance Study ◽  
Linear Free Energy ◽  
Intramolecular Hydrogen

Carbon-13 nmr chemical shifts have been used to determine the basicity constants for nine alcohols. The method involves comparing the chemical shifts for carbon atoms adjacent to the site of protonation with those for carbon atoms in a more remote position. The differences in the chemical shifts (Δ values) at different acidities are then used to calculate basicity constants for the alcohols. The pKBH+ values, determined by use of the "X function" are as follows: ethanol −2.12, 1-propanol −2.12, 3-chloro-1-propanol −2.24, 2-chloroethanol −2.45, 2-bromoethanol −2.41, 2-nitroethanol −2.09, 2-methoxyethanol −1.93, 2-phenoxyethanol −1.87, and 2-propanol −2.06. The typical slope parameter, m*, is 0.17. Two linear free energy correlations are obtained: when the alcohols are considered to be a series of monosubstituted ethanols, the Hammett plot has a slope of 0.65; when they are considered to be a series of mono- and disubstituted methanols, the slope is 1.7. Alcohols bearing oxygen-containing substituents are more basic than predicted by about 0.5 pK units, presumably because their conjugate acids can be stabilized by intramolecular hydrogen bonding.

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