Conformational analysis. LXXI. Calculation of nuclear magnetic resonance spectra by semiempirical methods. I. Proton chemical shifts in hydrocarbons

1971 ◽  
Vol 93 (16) ◽  
pp. 3894-3901 ◽  
Author(s):  
N. L. Allinger ◽  
M. Thomas Tribble ◽  
M. A. Miller
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Conformational Analysis ◽  
Chemical Shifts ◽  
Semiempirical Methods ◽  
Nuclear Magnetic Resonance Spectra ◽  
Proton Chemical Shifts ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

Carbon-13 and proton chemical shifts of cyclohexanes in relation to interaction energy

1970 ◽  
Vol 48 (16) ◽  
pp. 2639-2643 ◽  
Author(s):  
A. S. Perlin ◽  
H. J. Koch
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Interaction Energy ◽  
Electron Density ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Spectra ◽  
Proton Chemical Shifts ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

A comparison of nuclear magnetic resonance spectra for isomeric cyclohexane derivatives (methyl, hydroxyl, halogen) shows that net shielding of carbon-13 nuclei of these compounds increases additively with an increase in repulsive non-bonding interactions, and thus with decreasing enthalpy in the series. By contrast, an inverse shielding pattern is found for the appended protons. Hence, a destabilizing interaction in these compounds alters polarization of the C—H bond, placing greater electron density on carbon, and its impact appears to be delocalized over many C—H bonds of the molecule.

The metal nuclear magnetic resonance spectra of some tin(II) and lead(II) complexes with polydentate phosphines

1983 ◽  
Vol 61 (8) ◽  
pp. 1795-1799 ◽  
Author(s):  
Philip A. W. Dean
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Narrow Range ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The previously reported 1:1 complexes formed in MeNO2, between M(SbF6)2 (M = Sn or Pb) and Ph2P(CH2)2PPh2, PhP[(CH2)2PPh2]2, MeC(CH2PPh2)3, P[(CH2)2PPh2]3, and [Formula: see text] have been studied by metal (119Sn or 207Pb) nmr. The metal chemical shifts span the comparatively narrow range of −586 to −792 ppm and 60 to −269 ppm, relative to the resonance of MMe4, for 119Sn and 207Pb nmr, respectively. The implications of these data regarding the denticity of the ligand in M(P[(CH2)2PPh2]3)2+ are discussed, and a comparison with the metal nmr spectra of related stannous and plumbous complexes is made.

SOLVENT EFFECTS IN THE NUCLEAR MAGNETIC RESONANCE SPECTRA OF BENZALMALONONITRILES

1965 ◽  
Vol 43 (9) ◽  
pp. 2585-2593 ◽  
Author(s):  
M. A. Weinberger ◽  
R. M. Heggie ◽  
H. L. Holmes
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Solvent Effects ◽  
Benzene Solution ◽  
Chemical Shifts ◽  
Olefinic Proton ◽  
Solvent Molecule ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The nuclear magnetic resonance spectra of a series of substituted benzalmalononitriles were examined in various solvents. The chemical shifts for the olefinic protons are susceptible to large solvent effects which are interpreted as arising from association of a solvent molecule with the olefinic proton (acetone) or a site in its vicinity (benzene). With acetone this leads to a downfield shift from values observed in chloroform. In benzene solution the association produces increased shielding and is present in addition to a second solvation complex, the arrangement of which is governed by the substituent. The difference in behavior of the ethylenic proton in benzalmalononitriles from the formyl proton in benzaldehyde is ascribed to its more highly acidic nature.

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