11B- und 13C-NMR-Spektroskopie von nido-Hexaalkyl-2.3.4.5-tetracarbahexaboranen(6) / 11B- und 13C-NMR Spectroscopy of nido-Hexaalkyl-2,3,4,5-tetracarbahexaboranes(6)

1982 ◽  
Vol 37 (4) ◽  
pp. 412-419 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
Coupling Constants ◽  
Triple Resonance ◽  
Triple Resonance Experiments ◽  
Nmr Data ◽  
Nuclear Shielding ◽  
C Nmr

11B and 13C NMR data of peralkylated nido-2,3,4,5-tetracarbahexaboranes(6) are reported. Application of selective heteronuclear triple resonance experiments 13C{1H,11B} enables to assign the structures of various isomers. The magnitude of the coupling constants 1J(11B11B), 1J(13C11B) and 1J(13C13C) is in accord with expectations based on the conception of bonding in carboranes. The comparison of δ11B and δ13C data of the nido- 2,3,4,5-tetracarboranes(6) with δ13C-data of corresponding non-classical carbocations shows the influence of charge upon the nuclear shielding of carbon in the latter.

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.

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.

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.

A Novel Method for 13C-NMR Spectroscopy of Polymer in Emulsion: Quantitative Analysis of Microstructure of Crosslinked Polybutadiene in Latex

1999 ◽  
Vol 72 (5) ◽  
pp. 844-853 ◽  
Author(s):  
Seiichi Kawahara ◽  
Saori Bushimata ◽  
Takashi Sugiyama ◽  
Chihiro Hashimoto ◽  
Yasuyuki Tanaka
Keyword(s):  
Nmr Spectroscopy ◽  
High Resolution ◽  
13C Nmr ◽  
Lattice Relaxation ◽  
13C Nmr Spectroscopy ◽  
Lattice Relaxation Time ◽  
Solid Sample ◽  
Spin Lattice Relaxation ◽  
High Resolution Spectrum ◽  
C Nmr

Abstract A novel analytical method using high resolution 13C-NMR spectroscopy to study polymer latex, which is a heterogeneous system comprising polymer dispersoid and water, is described. The appropriate concentrations of surfactant and dried rubber content of a polybutadiene latex, which give the best spectrum, were found to be 1 w/v % and 10%, respectively. The half-widths of resonance peaks for the latex sample were almost identical to the half-widths obtained in solution, which were about one-third the width of those obtained using a solid sample of either a crosslinked or soluble polybutadiene. Nevertheless, the signal to noise ratio for the latex sample was slightly smaller than that for the solution sample. The values of spin-lattice relaxation time, T1, for the latex sample were similar to those for the solid sample. These demonstrate that the latex state C-NMR spectroscopy will be a powerful technique for structural characterization of crosslinked gels in the dispersoid because it gives a high resolution spectrum comparable to solution state spectroscopy, showing short T1 values corresponding to those for solid state C-NMR spectroscopy. High resolution latex state 13C-NMR spectroscopy was used to determine the concentrations of the various isomers of the polybutadiene in the dispersoid.

Extent of intramolecular cyclization in RAFT-synthesized methacrylic branched copolymers using 13C NMR spectroscopy

2015 ◽  
Vol 6 (7) ◽  
pp. 1143-1149 ◽  
Author(s):  
J. Rosselgong ◽  
S. P. Armes
Keyword(s):  
Nmr Spectroscopy ◽  
Intramolecular Cyclization ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
Branched Copolymers ◽  
C Nmr

The extent of intramolecular cyclization for a series of soluble branched methacrylic copolymers is determined by 13C NMR spectroscopy via deconvolution of oxymethylene carbon signals.

Ethylene Insertion with Soluble Ziegler Catalysts: Direct Insight into the Reaction Using Enriched 13C2 H4 and 13C NMR Spectroscopy II. The System Cp2TiMeCl/AlMeCl2/13C2H4

1985 ◽  
Vol 40 (2) ◽  
pp. 158-166 ◽  
Author(s):  
Gerhard Fink ◽  
Wolfgang Fenzl ◽  
Richard Mynott
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
Elementary Processes ◽  
Carbon Bond ◽  
Spectroscopic Evidence ◽  
Oligomer Distribution ◽  
Insight Into ◽  
C Nmr

Abstract The elementary processes involved in the polymerization of ethylene by soluble Ziegler catalysts of the type Cp2TiMeCl/AlMeCl2 have been studied by 13C NMR spectroscopy. Using 13C-enriched ethylene, detailed information was obtained directly on the system in the course of the polymerization. No spectroscopic evidence was found for precoordination of the monomer. The development of the oligomer distribution, which could be followed spectroscopically, proves that the mechanism proposed by Olivé cannot be correct. These experiments show conclusively that the ethylene is inserted into the titanium-carbon bond.

scholarly journals 1H- und 13C-NMR-spektroskopische Untersuchung an 1.4-Heteroarsenaniumsalzen / 1H and 13C NMR Spectroscopy of 1,4-Hetero-arsenanium Salts

1977 ◽  
Vol 32 (8) ◽  
pp. 908-911 ◽  
Author(s):  
Samir Samaan
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
1H And 13C Nmr ◽  
C Nmr

The synthesis of the 1,4-azarsenanium salts 3 and 6 is discribed. Conformation and configuration of the 1,4-oxa- and -azarsenanium salts have been studied via 1H and 13C NMR spectroscopy.

13C NMR Spectroscopy: A Brief Review

1972 ◽  
Vol 26 (1) ◽  
pp. 1-16 ◽  
Author(s):  
J. B. Stothers
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
13C Nmr Spectroscopy ◽  
Contributing Factors ◽  
C Nmr

An introduction to the chemical applications of 13C NMR spectroscopy is presented. The features of the basic instrumentation are outlined and a brief survey of 13C shieldings in hydrocarbons is given to show the general trends and to indicate the major contributing factors. Some recent applications are described to illustrate the potential of 13C techniques for solving chemical problems.

Sign in / Sign up

Export Citation Format

Share Document