Aromaticity of substituted cyclopropenes: A theoretical study

The aromaticity of several heterosubstituted cyclopropenes and corresponding protonated forms was investigated using ab initio calculations at the G2-MP2 level of theory, topological charge density, and NBO analysis. It was shown that according to geometric, energetic, charge density, and magnetic criteria these systems are remarkably aromatic, especially the protonated forms. It was shown that the aromatic delocalization of double bond in the cyclopropene ring can be well modeled using a three-center two-electron bond in the framework of NBO analysis proposed by Reed and Weinhold.