نتایج جستجو برای: aromaticity and rahb
تعداد نتایج: 16827345 فیلتر نتایج به سال:
The aryne [3 + 2] cycloaddition process with pyridinium imides breaks the aromaticity of the pyridine ring. By equipping the imide nitrogen with a sulfonyl group, the intermediate readily eliminates a sulfinate anion to restore the aromaticity, leading to the formation of pyrido[1,2-b]indazoles. The scope and limitation of this reaction are discussed. As an extension of this chemistry, N-tosyli...
In this study, an effort has been made to analyze the aromaticity of oligomers phenylenes and thiophenes, with presence absence linkers using Nucleus-Independent Chemical Shift (NICS) as a descriptor. The relation between HOMO–LUMO gaps, reorganization excitation energies respective NICS values employed develop structure-aromaticity-conjugation spectroscopy relationship (SACSR). Results show th...
In the free-electron model (FE) of cyclic polyenes the 7r-electrons are allowed to move freely in a ring. A modification of the FE-model (the MFE-model) is discussed in which the N-fold symmetry due to the N C-atoms of the ring is taken into account by an appropriate potential. The results of the MFE-model are compared with HMO-theory. The sequence of degenerate and non-degenerate levels which ...
The computational insights illustrate the intramolecular hydrogen bonding/stability versus aromaticity analyses of a variety several sets multi-substituted OH/SH benzenes using quantifying approaches (NICS, HOMA, PDI, and AIBIC for aromaticity) (Relative Energy, HOMO-LUMO gap, QTAIM, HBSBIC stability/hydrogen bond strength) in framework density function theory (DFT) approach ab initio calculati...
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