Photoelectron spectra and fluxional behaviour in some σ-cyclopentadienes

Abstract

A close correlation is shown to exist between fluxional behaviour in the σ-cyclopentadienes 5-RC₅H₅(R = H, CH₃, SiH₃, GeH₃, or SiF₃) and the relative positions of the two photoelectron bands due to the ring π-bonding electrons. For R = PF₂ and SiCl₃ interactions between the second ring level and non-bonding orbitals of R have to be taken into account. It is suggested that the fluxional behaviour arises from interaction of R–C₅σ-bonding level with the symmetric ring π-bonding level, which is greatest in those compounds that show fast fluxional behaviour.