1H and 13C chemical shift calculations for 12-oxa-pentacyclo[6.2.1.16,9.02,7.02,10]dodeca-4-eno systems using GIAO method at different levels of theory

Morisso, Fernando Dal Pont; Stassen, Hubert; Livotto, Paolo Roberto; Costa, Valentim Emı́lio Uberti

doi:10.1016/j.molstruc.2004.12.024

Cited by 3 publications

(2 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7b. The difference in the dihedrals can be associated with the conformational arrangement adopted by the anion, The calculated energies obtained for CSA and CSA anion were, respectively, −0.25901712 and −0.32376011 Hartrees, considering one Hartree as 627.5095 kcal/mol [25]. These energy values indicate that the geometry obtained by the anion is more stable than the acid geometry.…”

Section: Chemical Calculationsmentioning

confidence: 90%

“…Computations using the Austin Model 1 (AM1 semiempirical method) [22] have been conducted since the 1980s, yielding very good results, whereas the ab initio and DFT (density functional theory) methods are usually employed in the more consistent predictions of structural characteristics and molecular properties [23,24], magnetic parameters for NMR studies [25], and other subjects. Regarding particularly the conducting polymers, molecular orbital calculations using the ab initio method at the STO-3G* level of theory were used to select 2-methoxianiline-5-sulfonic acid in the construction of certain sulfonated polyanilines [26].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High-impact polystyrene/polyaniline membranes for acid solution treatment by electrodialysis: Preparation, evaluation, and chemical calculation

Amado

Rodrigues

Morisso

et al. 2008

Journal of Colloid and Interface Science

Self Cite

View full text Add to dashboard Cite

Section: Chemical Calculationsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

High-impact polystyrene/polyaniline membranes for acid solution treatment by electrodialysis: Preparation, evaluation, and chemical calculation

Amado

Rodrigues

Morisso

et al. 2008

Journal of Colloid and Interface Science

Self Cite

View full text Add to dashboard Cite

Aluminum alkoxide complexes from highly substituted 3,4‐epoxy alcohols: An NMR and computational study

Torres

Ishikawa

Prieto

2012

J of Physical Organic Chem

View full text Add to dashboard Cite

The organoaluminum mediated epoxide ring opening of epoxy alcohols is a key step in the oxirane-based approach for polypropionate synthesis. However, this reaction has shown unanticipated regioselectivities when applied to 2-methyl-3,4-epoxy alcohols. In order to gain mechanistic insight into the factors controlling the epoxide ring opening process, diastereomeric 2-methyl-3,4-epoxy alcohols were reacted with triethylaluminum in order to identify the aluminum complexes formed by these systems. Different epoxide-aluminum complexes were calculated using ab initio HF/[13s7p/11s5p] and B3PW91/6-31G** gauge-including atomic orbital (GIAO) methods and compared to the experimental NMR data. The calculated and experimental data correlates with the aluminum dimer complex (TIPSOCH 2 CH(OAlEt 2 )CH(CH) 3 CHCH(O)(AlEt 3 )) 2 (VIII) for the systems favoring the nucleophilic attack at the external C4 epoxide carbon, while an unusual trialuminum species TIPSOCH 2 CH(OAlEt 2 )CH(CH) 3 CHCH(O)(AlEt 3 ) 2 (X) is consistent with the systems favoring the internal C3 attack. The 27 Al NMR data established the tetracoordinated nature of the aluminum metal in all alkoxy aluminum intermediates, while the 13 C NMR data provided insight into the aluminum-oxygen coordination. The formation of the complexes was dictated by the stereochemical disposition of the substituents. These complexes are different from the generally accepted bidentate intermediates proposed for 2,3-epoxy alcohols and simpler 3,4-epoxy alcohols.

show abstract

A detailed experimental and theoretical study of two novel substituted trifluoromethylchromones. The influence of the bulky bromine atom on the crystal packing

León

Echeverría

Piro

et al. 2015

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

View full text Add to dashboard Cite

The new 3-methyl-2-trifluoromethylchromone (1) and 3-bromomethyl-2-trifluoromethylchromone (2) compounds were synthesized and characterized by vibrational (IR, Raman), UV-Vis and NMR ((1)H, (13)C and (19)F) spectroscopy and MS spectrometry. The crystal structures of 1 and 2 were determined by X-ray diffraction methods. Both compounds crystallize in the monoclinic P21/c space group with Z=4 molecules per unit cell. The structures were solved from 1423 (1) and 1856 (2) reflections with I>2σ (I) and refined by full-matrix least-squares to agreement R1-values of 0.0403 (1) and 0.0554 (2). Because of π-bonding delocalization, the organic molecular skeletons are planar and the molecular bonding structures can be described by formally single, double and resonant bonds. In 2, the CF3 group revealed a strong rotational disorder around the CCF3 bond, which could be explained in terms of four split positions with about uniform angular distribution. The vibrational, electronic and NMR, spectra were discussed and assigned with the assistance of DFT calculations.

show abstract

1H and 13C chemical shift calculations for 12-oxa-pentacyclo[6.2.1.16,9.02,7.02,10]dodeca-4-eno systems using GIAO method at different levels of theory

Cited by 3 publications

References 24 publications

High-impact polystyrene/polyaniline membranes for acid solution treatment by electrodialysis: Preparation, evaluation, and chemical calculation

High-impact polystyrene/polyaniline membranes for acid solution treatment by electrodialysis: Preparation, evaluation, and chemical calculation

Aluminum alkoxide complexes from highly substituted 3,4‐epoxy alcohols: An NMR and computational study

A detailed experimental and theoretical study of two novel substituted trifluoromethylchromones. The influence of the bulky bromine atom on the crystal packing

Contact Info

Product

Resources

About