Structural Evidence for Antiaromaticity in Free Boroles

Pentaphenylborole and a ferrocenylborole were synthesized and structurally characterized. Both experimental and theoretical data reveal that rather weak intermolecular interactions are able to significantly alter the bond lengths in the borole ring of pentaphenylborole (see picture). Moreover, the high Lewis acidity of boroles is demonstrated by a significant Fe⋅⋅⋅B interaction in the ferrocenylborole in the solid state. Supporting information for this article is available on the WWW under http: //www. wiley-vch. de/contents/jc₂002/2008/z704771ₛ. pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.