It is well known that singlet state aromaticity quite insensitive to substituent effects, in the case of monosubstitution. In this work, we use density functional theory (DFT) calculations examine sensitivity triplet effects. For purpose, chose antiaromatic cyclopentadienyl cation, antiaromaticity which reverses aromaticity, conforming Baird’s rule. The extent (anti)aromaticity was evaluated by...

A portfolio of photochemical transformations found in a variety areas can be rationalized through consideration either gain 4nπ-electron aromaticity or relief (4n+2) π-electron antiaromaticity excited states ππ* character. These back-of-an-envelope tools provided by Baird's rule serve as compass for excursions electronically states. More information the Review H. Ottosson and co-workers (DOI: 1...

Entirely unlike the aromatic closo BnHn2- borane dianions, isoelectronic Si62- and Si122- are antiaromatic. Their Oh and Ih symmetries are responsible, as the other deltahedral silicon dianion clusters do not exhibit this behavior. These high symmetries prevent mixing among the degenerate lone pair and skeletal orbitals, leading to paratropic behavior.

Substance containing two ?-congested aromatic systems are attractive targets in synthetic studies as well efforts designed to explore the unique properties that originate from ?-congestion. Since time of computational by Schleyer and Warner, concept stacked aromaticity created encounter antiaromatic rings has received much attention. A structure ?-congestion between norcorrole was prepared Shin...

An interesting feature of elemental boron and boron compounds is the occurrence of highly symmetric icosahedral clusters. The rich chemistry of boron is also dominated by three-dimensional cage structures. Despite its proximity to carbon in the periodic table, elemental boron clusters have been scarcely studied experimentally and their structures and chemical bonding have not been fully elucida...

Oxidation of m- and p-substituted benzylidene fluorenes to antiaromatic dications was attempted by electrochemical and chemical means. Electrochemical oxidation to dications was successful for benzylidene fluorenes with p-methoxy, p-methyl, p-fluoro, and unsubstituted phenyl rings in the 3-position; attempts to oxidize the m-substituted derivatives via electrochemistry were unsuccessful. Chemic...

Through-space isotropic NMR shielding values of a perpendicular diatomic hydrogen probe moved in a 0.5 Å grid 2.5 Å above several polycyclic aromatic/antiaromatic ring and aromatic/aromatic hydrocarbons were computed with Gaussian 03 at the GIAO HF/6-31G(d,p) level. Combinations of benzene fused with cyclobutadiene, with the tropylium ion, and with the cyclopentadienyl anion were investigated. ...