Barriers to internal rotation around the C–N bond in 3-(o-aryl)-5-methyl-rhodanines using NMR spectroscopy and computational studies. Electron density topological analysis of the transition states

2004 ◽  
Vol 2 (17) ◽  
pp. 2426-2436 ◽  
Author(s):  
Yeliz Aydeniz ◽  
Funda Oğuz ◽  
Arzu Yaman ◽  
Aylin Sungur Konuklar ◽  
Ilknur Doğan ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Internal Rotation ◽  
Electron Density ◽  
Topological Analysis ◽  
Transition States ◽  
Computational Studies ◽  
Barriers To Internal Rotation

scholarly journals Understanding the regio-and diastereoselective synthesis of a potent antinociceptive isoxazolidine from C-(pyridin-3-yl)-N-phenylnitrone in the light of molecular electron density theory

2020 ◽  
Vol 85 (6) ◽  
pp. 765-779
Author(s):  
Nivedita Acharjee
Keyword(s):  
Electron Density ◽  
Density Functional ◽  
Topological Analysis ◽  
Transition States ◽  
Cycloaddition Reaction ◽  
Aim Analysis ◽  
Conceptual Density Functional Theory ◽  
Covalent Interaction ◽  
Molecular Electron ◽  
Molecular Electron Density Theory

[3+2] cycloaddition reaction of C-(pyridin-3-yl)-N-phenylnitrone and 2-propen-1-ol yields stereochemically defined potent antinociceptive isoxazolidine derivative. Computational quantum calculations (CQC) are performed for this synthesis to predict the polar character, mechanism and selectivity within the framework of molecular electron density theory (MEDT). Topological analysis of the electron localization function (ELF) classifies the nitrone as a zwitter-ionic(zw-) type three atom component (TAC) showing absence of any pseudoradical or carbenoid centre. Four reaction channels corresponding to the possible regio- and stereoselective pathways are studied at DFT/ /B3LYP/6-311G(d,p) level of theory. The reaction follows one-step mechanism with asynchronous transition states and the computed activation energies agree well with experimental data. The reaction can be differentiated into nine ELF topological phases, with faster C?C bond formation. Global electron density theory (GEDT) at the favoured transition state and conceptual density functional theory (CDFT) indices at the ground state of the reagents indicate non-polar character. Non-covalent interactions are predicted by atoms-in-molecules (AIM) analysis and non-covalent interaction (NCI) plots at the transition states.

Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

1980 ◽  
Vol 45 (8) ◽  
pp. 2219-2223 ◽  
Author(s):  
Marie Jakoubková ◽  
Martin Čapka
Keyword(s):  
Catalytic Activity ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Electron Density ◽  
Phosphorus Atom ◽  
Proton Acceptor ◽  
Trimethylsilyl Group ◽  
Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

Revisiting the charge density analysis of 2,5-dichloro-1,4-benzoquinone at 20 K

2017 ◽  
Vol 73 (4) ◽  
pp. 654-659 ◽  
Author(s):  
Zhijie Chua ◽  
Bartosz Zarychta ◽  
Christopher G. Gianopoulos ◽  
Vladimir V. Zhurov ◽  
A. Alan Pinkerton
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Topological Analysis ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Total Electron Density ◽  
Total Electron ◽  
Structure Factors ◽  
Density Analysis ◽  
Experimental Charge Density

A high-resolution X-ray diffraction measurement of 2,5-dichloro-1,4-benzoquinone (DCBQ) at 20 K was carried out. The experimental charge density was modeled using the Hansen–Coppens multipolar expansion and the topology of the electron density was analyzed in terms of the quantum theory of atoms in molecules (QTAIM). Two different multipole models, predominantly differentiated by the treatment of the chlorine atom, were obtained. The experimental results have been compared to theoretical results in the form of a multipolar refinement against theoretical structure factors and through direct topological analysis of the electron density obtained from the optimized periodic wavefunction. The similarity of the properties of the total electron density in all cases demonstrates the robustness of the Hansen–Coppens formalism. All intra- and intermolecular interactions have been characterized.

Quantum mechanical calculations on barriers to internal rotation

1968 ◽  
Vol 11 (4) ◽  
pp. 344-357 ◽  
Author(s):  
M. -Cl. Moireau ◽  
A. Veillard
Keyword(s):  
Internal Rotation ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Barriers To Internal Rotation
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