the armaticity of 5 methylcytosine tautomers in the gas phase has been studied and the chemical structures of related tautomers are investigated . the electronic energy, enthalpy and free energy of each tautomer are also estimated at the b3lyp/6-31 g* // b3lyp/6-31 g* and mp2 / 6-31 g* // mp2 / 6-31 g* levels

Besides the most common form of aromaticity involving a π-ring, hexaiodobenzene and hexakis(phenylselenyl)benzene dications also present σ-aromaticity in outer ring formed by main group substituents. These two compounds are considered σ- π-double aromatic, their characterization is special interest to fields organic structural chemistry. In this work, we decided explore double substituted tropy...

The structure and properties of niobapyrimidinium complex were examined by density functionaltheory method (mpw1pw91). The effect of solvent on the structural parameters, frontier orbitalenergies and hyperpolarizability (tot) of this molecule has been explored. The thermodynamicproperties of the title compound at different temperatures have been calculated. Also, the parasubstitutionseffect on ...

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...

he aromatic behavior of the azo-linked cyclopentadienide derivatives have been revealed in various natural compounds. In Tthis research, density functional theory (DFT) calculations at the B3LYP level are used to optimize the geometry of the compounds. In addition, we were interested in the evaluation of the aromaticity of the selected compounds using nucleus independent chemical shifts NIC...

Cyclooctatetraene (COT), the first 4nπ-electron system to be studied, adopts an inherently nonplanar tub-shaped geometry of D2d symmetry with alternating single and double bonds, and hence behaves as a nonaromatic polyene rather than an antiaromatic compound. Recently, however, considerable 8π-antiaromatic paratropicity has been shown to be generated in planar COT rings even with the bond alter...

The HOMA (Harmonic Oscillator Model of Aromaticity) index, reformulated in 1993, has been very often applied to describe π-electron delocalization for monoand polycyclic π-electron systems. However, different measures of π-electron delocalization were employed for the CC, CX, and XY bonds, and this index seems to be inappropriate for compounds containing heteroatoms. In order to describe proper...