Bicyclobutadienylene (tricyclo[4.2.0.025]octa-1,3,5,7-tetraene)-eta5 -cyclopentadienylcobalt. A possible intermediate in the remarkable gas phase rearrangement of 1,2-diethynyl-eta4-cyclobutadiene-n5 -cyclopentadienylcobalt

Reaction products from the thermal rearrangement of cobalt complexed 1,2-diethynyl-cyclobutadienes were tentatively identified by spectral investigation of mixtures resulting from the photodesilation of all acetylenic silyl groups followed by column chromatography on neutral alumina. Mass spectral and chemical properties were used for the relative structure assignments. Several mechanisms are suggested but the true identity of the intermediates will require further research