Five‐Membered Metallacyclic Allenoids: Synthesis and Structure of Remarkably Stable Strongly Distorted Cyclic Allene Derivatives

Abstract

Metallocene lends a hand: Treatment of [bis(alkynyl)HfCp2] complexes with HB(C6F5)2 results in 1,1-hydroboration and subsequent carbon–carbon coupling to yield the corresponding metallacyclopenta-1,2-diene derivatives (see structure of the trimethylsilyl derivative; Hf brown, B red, Si blue, F green, C black). X-ray diffraction and a quantum chemical analysis reveal an electronic structure between a bent cyclic allene and a coordinated butenyne. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z705615_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.