Ralf Wesendrup, H. Schwarz
Feb 4, 1997
Citations
0
Influential Citations
40
Citations
Journal
Organometallics
Abstract
A catalytic cycle for the formation of benzene from butadiene and ethyne, mediated by Ru+ and Rh+ with a turnover number of 6 for the rhodium and 4 for the ruthenium system, has been realized in an FT-ICR mass spectrometry experiment. In the first step, dehydrogenation of butadiene by M+ generates MC4H4+ (M = Ru, Rh); this key intermediate reacts with ethyne to yield C6H6 and “bare” M+. Structural investigations of the MC4H4+ intermediate by CID and ion−molecule reactions suggest a metallacyclopentadiene for RuC4H4+ and a rhodium-cyclobutadiene complex as the most probable structures. In addition, C4H4 complexes of all other group 8 transition metal cations have been generated and reacted with ethyne. While FeC4H4+ and C2H2 also produce benzene and Fe+, the analogous complexes of Co+ and Ni+ are unreactive toward ethyne. The C4H4 complexes of Os+, Ir+, and Pt+ and ethyne give rise to MC6H4+ which probably correspond to the benzyne complexes of these metal ions.