The planarity and 10 π-electron aromaticity of the free cyclooctatetraene dianion (C 8 H 8 2− , COT 2−) have been questioned recently on the basis of conflicting density functional and second-order Møller−Plesset perturbation computations. Rigorous coupled-cluster methods are employed here to establish the structure and properties of COT 2−. Like many… (More)
The first example of a dyotropic rearrangement of an enantiomerically pure, conformationally unconstrained, vicinal dibromide confirms theoretical predictions: D and L-1,2-dibromo-1,2-diphenylethane racemise stereospecifically in refluxing benzene without crossover to the meso-isomer. An orbital analysis of this six-electron pericyclic process is presented.
Self-assembling building blocks like the 4-pyridone can exhibit extraordinary H-bond-aromaticity coupling effects. Computed dissected nucleus independent chemical shifts (NICS(1)zz), natural bond orbital (NBO) charges, and energy decomposition analyses (EDA) for a series of hydrogen (H-) bonded 4-pyridone chains (4-py)n (n = 2 to 8) reveal that H-bonding… (More)
Reduction of a 4,5,6-triphospharadialene gave the corresponding isolable dianionic species. Despite having two deltate dianion-like π-electrons delocalized over the central framework, its small NICS(0)(πzz) value (only -2.2 ppm) indicates only limited aromaticity.