نتایج جستجو برای: π electron delocalization

تعداد نتایج: 340883  

Journal: :Physical chemistry chemical physics : PCCP 2011
Gerardo Martinez-Guajardo Zeferino Gómez-Saldoval Daniel F Jana Patrizia Calaminici Clemence Corminboeuf Gabriel Merino

Here we explore in silico an alternative to make planar eight π-electron bare ring systems with substitutions of some cyclooctatetraene ring carbon atoms by heavier group 14 elements. We found that the most stable eight membered rings with formulae C(4)Si(4)H(8), C(4)Ge(4)H(8), and C(4)Sn(4)H(8) have a perfect planar structure, enhancing delocalization energy as compared to cot.

2012
Agata Martyniak Pawel Lipkowski Noel Boens Aleksander Filarowski

The ketoenamine-enolimine tautometic equilibrium has been studied by the analysis of aromaticity and electron-topological parameters. The influence of substituents on the energy of the transition state and of the tautomeric forms has been investigated for different positions of chelate chain. The quantum theory of atoms in molecules method (QTAIM) has been applied to study changes in the electr...

2016
Dani Setiawan Elfi Kraka Dieter Cremer

7 ABSTRACT: Vibrational frequencies can be measured and calculated with 8 high precision. Therefore, they are excellent tools for analyzing the electronic 9 structure of a molecule. In this connection, the properties of the local 10 vibrational modes of a molecule are best suited. A new procedure is described, 11 which utilizes local CC stretching force constants to derive an aromaticity 12 ind...

Journal: :The Journal of chemical physics 2014
Lluís Blancafort Alexander A Voityuk

Exciton delocalization and singlet excitation energy transfer have been systematically studied for the complete set of 16 DNA nucleobase dimers in their ideal, single-strand stacked B-DNA conformation, at the MS-CASPT2 level of theory. The extent of exciton delocalization in the two lowest (π,π(*)) states of the dimers is determined using the symmetrized one-electron transition density matrices...

Stability of the π-π stacking interactions in the Ben||N-substituted-coronene complexes was studied using the computational quantum chemistry methods (where Ben is benzene and || denotes π-π stacking interaction, and N-substituted-coronene is coronene molecule which substituted with different number of N atoms). The results reveal simultaneous effects of structure and number of Heteroatom on th...

Journal: :Chemistry: A European Journal 2022

Structural and electrochemical data for [Cp*Rh] complexes spanning three oxidation states demonstrate that the 9,9′-dimethyl-4,5-diazafluorene ligand, a notable but uncommon analogue of 2,2′-bipyridine, can stabilize electron-rich species through π-backbonding concomitant charge delocalization. This “fresh light” on bonding properties is reflected in photo recent vibrant sunset authors’ home ci...

Journal: :Química Nova 2021

In this study, we investigate the effects of nitrogen and boron dopants on properties phenalene/phenalenyl systems based Hückel theory by using Hueckel Molecular Orbital software. The configurations are graphitic, pyridinic, pyrrolic. electronic configuration bare phenalene confirms delocalization π electrons radical molecule, which is in good agreement with results previous studies. Dopant typ...

G. O. Oyeleke I. O. Abdulsalami K. A Alabi M. D. Adeoye,

The synthesis and characterization of 1, 3-bis [(furan-2-yl) methylene] urea (BFMU) and 1, 3-bis [furan-2-yl) methylene] thiourea (BFMT) have been reported by our research team. The effects of solvents polarity on their electronic transition energies (HOMO-LUMO) and associated qualitative structure activity relationship parameters (i.e. log P, ionization energies and global hardness) were inves...

2009
Bing-Yu Zhang Jing-Jing Nie Duan-Jun Xu

In the crystal structure of the title Ni(II) complex, [Ni(C(6)H(4)NO(3))(2)(C(3)H(4)N(2))(2)], the Ni(II) atom is located on a twofold rotation axis and is chelated by two oxidopyridiniumcarboxyl-ate anions and further cis-coordinated by two imidazole ligands in a distorted cis-N(2)O(4) octa-hedral geometry. The C-O bond distance of 1.2573 (19) Å found for the non-coordinating O atom of the car...

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