Comment on the X-Ray Structure of Pentamethylcyclopentadienyl Cation

Not C5Me5+ (II): The search for the elusive singlet cyclopentadienyl cation must continue. Quantum-mechanical calculations of both structure and NMR chemical shifts suggest that the recently reported X-ray structure is that of a cyclopentenyl cation (see picture). Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2002/c20053_s.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.