Reactivity of co-ordinated ligands. Part XXV. Tritylcyclo-octatetraene derivatives of tricarbonyliron and protonation of tricarbonyl(η-tritylcyclo-octatetraene)iron

Abstract

The protonation of tricarbonyl(η-tritylcyclo-octatetraene)iron, (VI), at 10 °C yields the cation tricarbonyl(1–5-η-6-tritylcyclo-octa-2,4,6-trienylium)iron, (IX). Tritylation of tricarbonyl(η-cyclo-octatetraene)iron. (IV), yields the cation tricarbonyl(1–5-η-8-tritylcyclo-octa-2,4,6-trienylium)iron, (V). Both cations have been observed by ¹³C and ¹H n.m.r. spectroscopy. Deprotonation of cations (V) and (IX) by base yields (VI). At 160 °C complex (VI) isomerizes to tricarbonyl(2,3:4,5-η-7-tritylbicyclo[4.2.0]octa-2,4,7-triene)iron, (VII). Reaction of complex (VI) or (VII) with Ce⁴⁺ in ethanol yields tritylcyclo-octatetraene,(VIII), in good yield. The ¹³C and ¹H n.m.r. spectra of (V)—(IX) are reported.