Polarized Mössbauer absorption studies on single crystals of bis(η-cyclo-pentadienyl)iron

Abstract

The orientation of the electric-field gradient (e.f.g.) tensor at the iron nucleus in [Fe(η-C₅H₅)₂](ferrocene) has been determined by polarized Mössbauer measurements. The tensor is axially symmetric with the principal axis along the molecular axis. The molecules gradually rotate by ca. 20° in the vicinity of the λ transition at 164 K. A possible packing arrangement in the low-temperature phase has been devised which accounts for many of the observed properties.