ChemInform Abstract: CHOICE OF NUCLEAR MAGNETIC RESONANCE VICINAL PROTON-PROTON AND VICINAL CARBOXYLATE CARBON-13-PROTON COUPLING CONSTANT PARAMETERS FOR ESTIMATING CONFORMATIONS IN AMINO ACIDS

1979 ◽  
Vol 10 (51) ◽  
Author(s):  
R. B. MARTIN
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Coupling Constant ◽  
Proton Proton ◽  
Proton Coupling ◽  
Vicinal Proton ◽  
Nuclear Magnetic

An NMR study of steric and hyperconjugative barriers in benzyl X(CH3)3, X = C, Si, Ge, Sn, Pb

1989 ◽  
Vol 67 (8) ◽  
pp. 1283-1287 ◽  
Author(s):  
Ted Schaefer ◽  
Glenn H. Penner ◽  
Craig S. Takeuchi ◽  
Christian Beaulieu
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Long Range ◽  
Coupling Constant ◽  
Proton Proton ◽  
Proton Coupling ◽  
Nmr Study ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The 1H nuclear magnetic resonance spectra and their analyses are reported for benzyltrimethyl X (X = C, Si, Ge, Sn, Pb) and for the 2,6-dichloro derivatives where X = Si, Ge, Sn, Pb. The steric barrier to rotation about the Csp2—Csp3bond for X = C, based on the long-range proton–proton coupling constant over six bonds, 6J(H,CH2), must be greater than 20 kJ/mol. Unexpectedly, 6J(H,CH2) implies that the barriers for X = Si, Ge, Sn, Pb have relatively minor steric components. If these barriers are dominated by hyperconjugative interactions of the C—X bond with the aromatic π system, then they are probably mainly twofold in nature. Furthermore, their magnitude is likely to be near 9.5 kJ/mol for X = Si, Ge, Sn and may be as high as 12 kJ/mol for X = Pb. Keywords: NMR, benzyl X(CH3)3, X = C, Si, Ge, Sn, Pb; NMR, conformations; NMR, hyperconjugation.

scholarly journals Carbon 13 Nuclear Magnetic Resonance of Pentapeptides of Glycine Containing Central Residues of Aliphatic Amino Acids

1973 ◽  
Vol 248 (17) ◽  
pp. 6104-6113 ◽  
Author(s):  
Philip Keim ◽  
Robert A. Vigna ◽  
Robert C. Marshall ◽  
Frank R.N. Gurd
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nuclear Magnetic
Sign in / Sign up

Export Citation Format

Share Document