Stereomanipulation of (η5-1-Arylcyclohexadienyl)iron Complexes

A crystallographic investigation comparing five 1-aryl-substituted tricarbonyl[(1–5-?)-cyclohexadienyl]iron(1+) salts demonstrates that introducing additional electron density on the aromatic ring increases p overlap between the arene and the cyclohexadienyl ligand, thus flattening the structures sufficiently to make available a conformation in which nucleophiles can approach the site of substitution, despite the steric blockade of o-benzyl substituents