منابع مشابه
Local aromaticity of the five-membered rings in acenaphthylene derivatives.
In this paper, a detailed study of the local aromaticity in a series of cyclopenta-fused linear polyacenes (acenaphthylene derivatives) was performed using several different criteria of aromaticity. Namely, the energy effect (ef), bond resonance energy (BRE), harmonic oscillator model of aromaticity (HOMA) index, multi centre delocalization indices (MCI), electron density at ring critical point...
متن کاملSubstituent effects on the aromaticity of carbocyclic five-membered rings.
The influence of the substituent nature, as well as the number and position of the substituents, on the aromaticity/antiaromaticity of a comprehensive set of derivatives of cyclopentadienyl anion, cyclopentadiene and cyclopentadienyl cation has been analyzed. The aromaticity/antiaromaticity of substituted cyclopentadienyl derivatives has been measured using energetic, magnetic and structural cr...
متن کاملLocal aromaticity of the six-membered rings in pyracylene. A difficult case for the NICS indicator of aromaticity.
In this work, we have analyzed the local aromaticity of the six-membered rings (6-MRs) of planar and pyramidalized pyracylene species through the structurally based harmonic oscillator model of aromaticity (HOMA), the electronically based para-delocalization index (PDI), and the magnetic-based nucleus independent chemical shift (NICS) measurements, as well as with maps of ring current density. ...
متن کاملElectronic structure of N₂P₂ four-membered rings.
The biradicaloid character of the ground-state structures of N2P2 rings is studied by using the high-level ab initio multiconfigurational CASPT2/CASSCF method. In order to obtain accurate descriptors, we combine two criteria: 1) singlet-triplet energy gaps and 2) relative values of the occupation numbers for bonding and antibonding orbitals associated with the radical sites. The singlet-triplet...
متن کاملMagnetic Circular Dichroism (MCD) of Four-membered Rings with four jr-Electrons
Michl extended the perimeter model of cyclic ^-electron systems, which was originally developed by Piatt [ 1 ] and Moffit [2], to the interpretation of absolute signs in magnetic circular dichroism (MCD) [3-5], A set of rules was derived by him that accounted for a large number of MCD signs in the spectra of all kinds of aromatic JTsystems, i.e. those derived from a (4/V+2)-electron perimeter. ...
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ژورنال
عنوان ژورنال: Journal of the American Chemical Society
سال: 1990
ISSN: 0002-7863,1520-5126
DOI: 10.1021/ja00167a009