10B-, 11B-, 13C-NMR-Untersuchungen von closo-Pentaalkyl-1.5-dicarbapentaboranen(5) / 10B-, 11B-, 13C NMR Studies of closo-Pentaalkyl-1,5-dicarbapentaboranes(5)

1981 ◽  
Vol 36 (6) ◽  
pp. 704-707 ◽  
Author(s):  
Roland Köster ◽  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Chemical Shifts ◽  
Parent Compound ◽  
Coupling Constants ◽  
Mo Calculations ◽  
Nmr Studies ◽  
Nmr Parameters ◽  
Alkyl Substitution ◽  
C Nmr

AbstractNMR parameters [chemical] shifts (δ11B, δ13C) and coupling constants (1J(13C1H), 1J(13C11B), 1J(13C13C), 1J(11B11B) of closo-pentaalkyl-1,5-dicarbapentaboranes(5) were determinated by 10B, 11B, and 13C NMR spectroscopy. The magnitudes of 1J(13C11B) and 1J(13C13C) correspond to 1J(11B1H), 1J(13C11B) and 1J(13C1H) in the parent compound 1,5-C2B3H5 . According to predictions from MO calculations 1J(11B11B) was found to be < 10 Hz. Together with these data the δ11B and δ13C values show that neither the structure nor the bonding situation in the polyhedron are significantly affected by alkyl substitution.

scholarly journals 13C NMR of the Tetrakis(phenylethynyl)borate Anion and of Some Phenylethynyl Boranes

1982 ◽  
Vol 37 (6) ◽  
pp. 788-789 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
13C Nmr ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Triple Resonance ◽  
Triple Resonance Experiments ◽  
Nmr Parameters ◽  
C Nmr

Abstract The 13C NMR parameters of the title compounds are assigned by heteronuclear triple resonance experiments 13C{1H,11B}. The magnitude of the coupling constants J(13C11B) corresponds roughly with J(13C13C). The chemical shifts δ13C reveal B-C(pp) π bonding which is, however, rather weak when compared with C+-C(pp) π bonding in phenylethynyl carbocations.

13C-NMR-Untersuchiingen an einigen Organosilanen /13 C NMR Studies on Some Organosilanes

1979 ◽  
Vol 34 (9) ◽  
pp. 1270-1274 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Werner Biffar
Keyword(s):  
13C Nmr ◽  
Structural Features ◽  
Coupling Constants ◽  
Coupling Mechanism ◽  
Nmr Studies ◽  
Nmr Parameters ◽  
Nmr Data ◽  
Fermi Contact ◽  
Fermi Contact Term ◽  
C Nmr

Abstract13C-NMR data (δ13C, J(13C1H), J(13C13C), J(29Si13C)) of noncyclic organosilanes CH4-n[Si(CH3)3]n (n = 1-4), (CH3)4-nC[Si(CH3)3]n (n = 1, 3, 4) and cyclic organosilanes [(CH3)2SiCH2]n (n = 2, 3), (CH3)2Si(CH2)3 are reported. Comparison of reduced coupling constants 1K proves the Fermi-contact-term to be the dominant coupling mechanism. Structural features of the four-membered heterocycles become apparent by comparison of their 13C NMR parameters with those of corresponding cycloalkanes, noncyclic organo­silanes and the 1,3,5-trisilacyclohexane derivative.

13C NMR spectra of sodium naphthalenesulphonates

1985 ◽  
Vol 50 (8) ◽  
pp. 1852-1861 ◽  
Author(s):  
Dobroslav Šnobl ◽  
Antonín Lyčka ◽  
Jaroslav Horyna
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Deuterium Oxide ◽  
Coupling Constants ◽  
13C Nmr Spectra ◽  
Nmr Parameters ◽  
Measured Effect ◽  
C Nmr

13C NMR spectra of thirteen sodium naphthalenesulphonates have been measured in deuterium oxide. The 13C chemical shifts have been assigned, and the nJ(13CH) coupling constants have been measured. Effect of SO3(-) group on the 13C NMR parameters is discussed.

Preparation, 1H and 13C NMR, and ab initio/IGLO study of mono-O-protonated deltic acid and theoretical investigation of di-, tri-, and tetra-O-protonated deltic acids

1999 ◽  
Vol 77 (5-6) ◽  
pp. 525-529 ◽  
Author(s):  
GK Surya Prakash ◽  
Golam Rasul ◽  
George A Olah ◽  
Ronghua Liu ◽  
Thomas T Tidwell
Keyword(s):  
Nmr Spectroscopy ◽  
Ab Initio ◽  
Theoretical Investigation ◽  
13C Nmr ◽  
Chemical Shifts ◽  
1H And 13C Nmr ◽  
Nmr Chemical Shifts ◽  
Molar Solution ◽  
Protonated Species ◽  
C Nmr

The hitherto elusive mono-O-protonated deltic acid C3O3H3+ was prepared by protolysis of di-tert-butoxy deltate in FSO3H-SO2ClF and in FSO3H:SbF5 (Magic Acid; 1:1 molar solution) in SO2ClF as solvent at -78°C and was characterized by 1H and 13C NMR spectroscopy. The structure and NMR chemical shifts were also calculated by the ab initio/IGLO method. No NMR evidence was found for persistent di-O-protonated deltic acid under these conditions, although a limited equilibrium with the mono-O-protonated species can be involved. Di-, tri-, and tetra-O-protonated deltic acids were also studied by ab initio/IGLO method.Key words: protonated deltic acid, aromaticity, superacids, NMR spectroscopy, ab initio and IGLO calculations.

Organoboranes and tetraorganoborates studied by 11B and 13C NMR spectroscopy and DFT calculations

2015 ◽  
Vol 70 (6) ◽  
pp. 421-424 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
Dft Calculations ◽  
13C Nmr ◽  
Quantum Chemical ◽  
13C Nmr Spectroscopy ◽  
Coupling Constants ◽  
Line Widths ◽  
Nmr Signals ◽  
C Nmr ◽  
Extract Information

AbstractCare should be taken on recording the sometimes elusive 13C NMR signals for boron-bonded carbon atoms, since it is easy to extract information about coupling constants 1J(13C,11B) by measuring the respective line widths of 13C(B-C) and 11B NMR signals. This information can be confirmed by quantum-chemical calculations [B3LYP (6-311+G(d,p) level of theory] of nJ(13C,11B) in organoboranes and tetraorganoborates. For the latter, the signs for n = 2, 3, 4 were experimentally determined.

Chemical and 13C NMR Studies of a Rhamnoarabinogalactan from the Leaves of Plantago lanceolata L. var. libor

1994 ◽  
Vol 59 (12) ◽  
pp. 2714-2720 ◽  
Author(s):  
Alžbeta Kardošová ◽  
Peter Capek
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Plantago Lanceolata ◽  
Partial Hydrolysis ◽  
Side Chains ◽  
Methylation Analysis ◽  
Nmr Studies ◽  
C Nmr

A rhamnoarabinogalactan isolated from the leaves of Plantago lanceolata L. var. libor has been investigated by methylation analysis, partial hydrolysis, and 13C NMR spectroscopy. The structural conclusions obtained by 13C NMR measurements were consistent with the data from methylation analysis. The polysaccharide has a β-(1→6)-D-galactan core branched on O-3 by side chains of (1→5)-linked α-L-arabinofuranosyl units, some of which bear in position O-5 terminal β-D-galactopyranosyl residues. L-Rhamnose occurs as nonreducing ends.

Hochauflösungs-13C-NMR-Spektroskopie, VI [1]. Strukturabhängigkeit der 13C,H-Kopplungskonstanten in 6.6-disubstituierten Fulvenen / High Resolution 13C NMR Spectroscopy, VI [1]. Structure Dependence of the 13C,H Coupling Constants in 6,6-Disubstituted Fulvenes

1980 ◽  
Vol 35 (12) ◽  
pp. 1572-1574 ◽  
Author(s):  
Siegmar Braun ◽  
Ulrich Eiehenauer
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectroscopy ◽  
High Accuracy ◽  
Coupling Constants ◽  
Complete Analysis ◽  
Structure Parameters ◽  
Structure Dependence ◽  
C Nmr

In order to study the structure dependence of the 13C,H couplings in the fulvene system the 1H-coupled 13C NMR spectra of 6,6-disubstituted fulvenes (R = R′ = C6H5, CH3, cyclopropyl and N(CH3)2) were recorded and the interesting couplings determined with high accuracy by complete analysis. They have values typical for unsaturated five membered rings with vastly localised double bonds like cyclopentadiene-1,3 and spiro[2.4]heptadiene- 4,6 and show characteristic correlations with structure parameters.

Bonding in Cyclobutabenzene Chromium Tricarbonyl Complexes Studied by 13C NMR. Evidence of π-Bond Localization from 1J(13C,13C)

1995 ◽  
Vol 50 (4) ◽  
pp. 483-487 ◽  
Author(s):  
H. Butenschön ◽  
B. Gabor ◽  
R. Mynott ◽  
H. G. Wey
Keyword(s):  
13C Nmr ◽  
Coupling Constants ◽  
Chromium Tricarbonyl ◽  
Chromium Complex ◽  
Nmr Parameters ◽  
Chromium Tricarbonyl Complexes ◽  
The One ◽  
Bond Localization ◽  
Insight Into ◽  
C Nmr

The 13C NMR parameters of several cyclobutabenzenes ( 1a - 1e ) and their corresponding complexes (cyclobutabenzene)M(CO)3 (M = Cr, Mo, W, 2 - 4 ) are presented and discussed. Two cyclobutabenzenes 1b and 1d and their chromium tricarbonyl complexes 2b and 2d have been examined in greater detail: the signal assignments have been confirmed by 2 D-INADEQUATE and the one bond coupling constants 1J(13C ,13C) measured at natural abundance using 1 D-INADEQUATE . Although the results provide no insight into why the chromium complex of 1,2 - dioxocyclobutabenzene (1e) is much more reactive at the keto groups than 1e itself, they do reveal a weak but not negligible alternation of the carbon s-character in the C - C bonds of the 6-membered rings both in the free cyclobutabenzenes and in the complexes, thus providing evidence for slight bond fixation (Mills-Nixon effect).

FT-IR and 13C-NMR Correlations for Some N-Substituted Azoles and Benzazoles

1995 ◽  
Vol 49 (8) ◽  
pp. 1111-1119 ◽  
Author(s):  
José Elguero ◽  
Manuel Gil ◽  
Nerea Iza ◽  
Carmen Pardo ◽  
Mar Ramos
Keyword(s):  
Carbon Tetrachloride ◽  
13C Nmr ◽  
Empirical Equation ◽  
Chemical Shifts ◽  
Statistic Analysis ◽  
Spectral Parameters ◽  
Nmr Parameters ◽  
Hammett Constants ◽  
Ft Ir ◽  
C Nmr

The FT-IR (in carbon tetrachloride) and 13C-NMR (in deuterochloroform) spectra of six p-substituted aniline derivatives, as reference compounds, and nine 1- p-aminophenyl-azoles and benzazoles were recorded. The measured spectral parameters from FT-IR were symmetric, vs(NH2), and antisymmetric, vas(NH2), stretching fundamentals and their band intensity ratio, A( vas)/ A( vs), while the corresponding 13C-NMR parameters were C-1 to C-4 chemical shifts of 1- p-aminophenyl carbons. Different IR and 13C-NMR spectral parameters and Hammett constants σp (or σp-) were correlated, and statistic analysis of the results permitted an estimation of σp values of the nine (azol-1-yl) substituents. An empirical equation to calculate the Hammett constants of new azoles and benzazoles is proposed.

Sign in / Sign up

Export Citation Format

Share Document