Planarization of 1,3,5,7-cyclooctatetraene as a result of a partial rehybridization at carbon atoms: an MP2/6-31G∗ and B3LYP/6-311G∗∗ study

Recent Studies on the Aromaticity and Antiaromaticity of Planar Cyclooctatetraene

“…The small value is in line with the expected nonaromatic character due to the bent structure. On the other hand, effect of bending of the C=C-H angle directed toward the double bond in D 2d COT was investigated [44]. The bending of the C=C-H angle causes increase of NICS value with increasing planarity of the COT ring and decreasing HOMO-LUMO gap.…”

How the Substituent Effect Influences π-Electron Delocalisation in the Ring of Reactants in the Reaction Defining the Hammett Substituent Constants σm and σp

“…Thus geometry may be a source of reliable information on the electron distribution, and employing appropriate references, may be used for description of π-electron delocalization. Thus aromaticity index HOMA [6,7] may be used firmly [11] for estimation of π-electron delocalisation except in a few cases like planarized cyclooctatetraene [12] and alike [13]. The extended form of HOMA [7] allows one to get information about the nature of dearomatisation.…”

Structural stability and electronic property of C68X4 (X=H, F, and Cl) fullerene compounds

“…The hybrid B3LYP functional (formed by combining Becke's three parameter nonlocal hybrid exchange functional [37] and the nonlocal correlation functional of Lee-Yang-Parr, [29]) in combination with 6-311G(d, p) basis set within GAUSSIAN 03 package [38] are used to compute the NICS values of C 68 X 4 compounds, and the accuracy and efficiency of this theoretical method have been verified by many previous calculations. [39,40] To measure the strain relaxation of C 68 X 4 (X = H, F, and Cl) derivatives caused by additional reactions, the pyramidalization angle (Â p ) [41,42] is calculated using the -orbital axis vector approach (POAV) as implemented in the Mol2Mol program [43].…”