Arsole Aromaticity Revisited

Lett. Org. Chem. 2 (2005) 469–474.

Mikael P. Johansson, Jonas JusÚlius

Department of Chemistry, Laboratory for Instruction in Swedish, P.O. Box 55, University of Helsinki, FI-00014 Helsinki, Finland

Abstract

The aromaticity of arsoles has been debated in the literature for years. Some measures indicate arsole to be non-aromatic, others attribute at least slight aromaticity to the molecule. Here, we take a ring-current view of aromaticity, and study arsole in more detail. We make comparisons to the nitrogen analogue pyrrole, the phosphorous analogue phosphole, and the carbon analogue cyclopentadiene. The newly developed gauge-including magnetically induced currents (GIMIC) method provides a direct measure of the current flow in molecules. Using GIMIC, we show that arsole indeed is almost half as aromatic as pyrrole. Phosphole comes in between. Even cyclopentadiene is found to possess a moderately strong induced ring current, thus questioning the accepted classification of this molecule as a non-aromatic reference system.

[ring current of arsole]


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