Conformational Preference of 2,2’-Dinitrodiphenyl as Determined by Proton NMR Spectroscopy

Valence Shell Electron-Pair Repulsion (VSEPR) theory has been regarded for decades as a highly successful, albeit nonquantitative model used to predict molecular geometries. 1 The VSEPR model bases its conjectures on the simple modeling of repulsive forces between electron pairs surrounding a central atom. As two charges of the same sign—positive or negative—are brought closer together, each charge feels a greater and greater repulsive force due to the electric field produced by the other charge. Under simple electrostatic treatment 2 : This general idea can be likened to electron pairs, atoms, or substituents in a molecule: these differing electron ―clouds‖ tend to orient themselves in a way so that the least amount of repulsion between their respective charges occurs. 3 By combining the predicted models of multiple central atoms, one can obtain a reasonable picture of conformation: how a more complex molecule will be oriented in space.