Evidence for a 1,3-sigmatropic shift in a fluxional organometallic system, trans,trans-1,4-bis(dicarbonyl-π-cyclopentadienyliron)buta-1,3-diene: nuclear magnetic resonance study

Abstract

The structure of the ¹³C satellite lines in the ¹H n.m.r. spectrum of trans,trans-1,4-bis(dicarbonyl-π-cyclopentadienyliron)buta-1,3-diene (I) and the dimethyl derivative (II) indicates that the fluxional process in these molecules involves mainly 1,3-shifts of the metal–carbon bonds: the n.m.r. spectrum of the monomethyl derivative (III) supports this conclusion.