On account of an interest to study the effect of a transition metal on the spin state of a carbene , we have investigated the reactions of some a-ferrocenyl carbenes in these years. A recent report by M. Cais et al. (1) on a possible formation of ferrocenyl carbene in the deprotonation of ferrocenyl carbonium ion prompted us to report our results on the chemistry of ferrocenyl carbenes. The thermal decomposition of benzoylferrocene tosylhydrazone sodium salt (Ia), prepared in situ by a reaction of corresponding hydrazone (mp 166.5'(decanp)) with sodium hydride, was carried out in pyridine-cyclohexene at 80". Although the isolation of diazo compound IIa was unsuccessful , its intermittent formation was indicated by IR (2060cm-'). (2) There were isolated benzylferrocene*(IVa, mp 75-76', 2%),(3) . diastereomers of 1,2-diferrocenyl-1,2-diphenylethane* (Va, mP 217-220's Ia,b (a:R=CsHs; b:R=CHa) IIa,b IIIa,b IVa,b Va,b VIa,b * The material with an asterisk was confirmed by a comparison with authentic specimen. The compounds without it were characterized by elemental analysis, IR, W, and nmr spectroscopy. The melting points are uncorrected.