Synthesis of ferrocenylvinylcyclopropene and its transformation into cyclopentadiene

Dehydrobromination of 2-bromo-1-ferrocenyl-1-(2-ferrocenyl-1-methylvinyl)cyclopropane results in 3-ferrocenyl-3-(2-ferrocenyl-1-methylvinyl)cyclopropene and its transformation product, viz., 1,4-diferrocenyl-5-methylcyclopentadiene. These compounds were characterized by 1H-, 13C-NMR, IR, UV–Vis spectroscopy and mass spectrometry. The structure of diferrocenylcyclopentadiene was determined by X-ray diffraction analysis.