Trimethylcyclohexane: overtone spectrum, ab initio calculations, and unusual chemical shifts

1991 ◽  
Vol 95 (4) ◽  
pp. 1579-1585 ◽  
Author(s):  
Kathleen M. Gough ◽  
Bryan R. Henry ◽  
Bernhard J. Schattka ◽  
Timothy A. Wildman
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Shifts

Some ab Initio Calculations on Indole, Isoindole, Benzofuran, and Isobenzofuran

1974 ◽  
Vol 29 (4) ◽  
pp. 624-632 ◽  
Author(s):  
J. Koller ◽  
A. Ažman ◽  
N. Trinajstić
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Shifts ◽  
Dipole Moments ◽  
Molecular Properties ◽  
Ionization Potentials ◽  
Charge Densities ◽  
Homo Lumo

Ab initio calculations in the framework of the methodology of Pople et al. have been performed on indole, isoindole, benzofuran. and isobenzofuran. Several molecular properties (dipole moments, n. m. r. chemical shifts, stabilities, and reactivities) correlate well with calculated indices (charge densities, HOMO-LUMO separation). The calculations failed to give magnitudes of first ionization potentials, although the correct trends are reproduced, i. e. giving higher values to more stable isomers. Some of the obtained results (charge densities, dipole moments) parallel CNDO/2 values.

Cluster Models and ab Initio Calculations of19F NMR Isotropic Chemical Shifts for Inorganic Fluorides

2005 ◽  
Vol 109 (20) ◽  
pp. 10270-10278 ◽  
Author(s):  
Monique Body ◽  
Gilles Silly ◽  
Christophe Legein ◽  
Jean-Yves Buzaré
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Shifts ◽  
Cluster Models ◽  
Isotropic Chemical Shifts ◽  
Inorganic Fluorides

Ab initio calculations on zinc porphyrins complexed to amines: geometrical details and NMR chemical shifts

2000 ◽  
Vol 531 (1-3) ◽  
pp. 381-386 ◽  
Author(s):  
R.M Gomila ◽  
D Quiñonero ◽  
A Frontera ◽  
P Ballester ◽  
P.M Deyà
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Shifts ◽  
Nmr Chemical Shifts ◽  
Zinc Porphyrins

Ab initio calculations for XPS chemical shifts of poly(vinyl-trifluoroacetate) using trimer models

2011 ◽  
Vol 605 (15-16) ◽  
pp. 1516-1524 ◽  
Author(s):  
Dominik Kröner ◽  
Christopher Ehlert ◽  
Peter Saalfrank ◽  
Andreas Holländer
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Shifts

Accurate ab initio calculations of O–H⋯O and O–H⋯−O proton chemical shifts: towards elucidation of the nature of the hydrogen bond and prediction of hydrogen bond distances

2015 ◽  
Vol 13 (33) ◽  
pp. 8852-8868 ◽  
Author(s):  
Michael G. Siskos ◽  
Andreas G. Tzakos ◽  
Ioannis P. Gerothanassis
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Chemical Shifts ◽  
Bond Lengths ◽  
Sensitive Measure ◽  
Proton Chemical Shifts

Ab initio calculations of O–H⋯O and O–H⋯−O 1H chemical shifts provide accurate electronic description of hydrogen bonding and sensitive measure of hydrogen bond lengths.

Analysis of magnesium–carbon bonding in magnesium anthracene systems

1996 ◽  
Vol 74 (6) ◽  
pp. 801-809 ◽  
Author(s):  
Ralf Stegmann ◽  
Gernot Frenking
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Density ◽  
Chemical Shifts ◽  
Topological Analysis ◽  
Nbo Analysis ◽  
Experimental Values ◽  
A Charge ◽  
Good Agreement ◽  
Carbon Bonding

Ab initio calculations at the MP2/3-21G(*) level of theory have been carried out for the magnesium–anthracene complexes 9,10-magnesiumanthracene•3H2O (1) and the 9-methyl (2), dimethyl (3), and 9,10-bis(methylsilyl) (4) substituted derivatives. The theoretically predicted geometries of the anthracene ligands are also reported. The calculated geometries of 1–4 are in very good agreement with experimental values for the corresponding THF complexes. The Mg—C9,10 bonds of the bridged structures are rather long and the anthracene ligands are folded by ~40° along the C9–C10 line in the complexes. Analysis of the electronic structure shows clearly that the Mg—C9,10 bonds should be considered as purely ionic. This is revealed by topological analysis of the electron density distribution and its associated Laplacian. The electron density at the Mg—C9,10 bond critical points ρ(rb) is very low and the Laplacian [Formula: see text] and the energy density Hb have positive values. The ionic nature of the Mg—C9,10 bond is also indicated by the natural bond order (NBO) analysis, which gives a Lewis structure with two lone pairs at C9 and C10 but no Mg—C9,10 bonds. The NBO method gives a charge donation from Mg to the anthracene ligand of nearly two. The theoretically predicted NMR chemical shifts using the GIAO method give 13C resonances for the complex 1 and for anthracene and anthracene dianion that are in good agreement with experimental values. Key words: magnesium–anthracene complexes, ab initio calculations, analysis of magnesium–carbon bonding.

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