The impact of intramolecular H-bonding on the aromatic character of substituted penta-fulvenes

The influence of the intramolecular H-bonding formation on the aromaticity of some substituted penta-fulvenes is investigated using magnetic (NICS(0), NICS(1) and NICS(1)zz), geometrical (HOMA) and electronic (FLU and SA) criteria to consider the multidimensional character of aromaticity. It is found that the formation of intramolecular hydrogen bond changes aromatic character of a substituted penta-fulvene. The variations of SA and HOMA indices due to the formation of intramolecular H-bondig significantly correlate with the properties of the considered hydrogen bond, while the other indices do not give any meaningful results. It seems that the hydrogen bond influences the geometrical and electronic dimensions of aromaticity.