Tricarbonyl[8-acetyl 2-4:6-7-η-bicyclo[3.2.1]octadienylium]iron, a novel rearrangement in the acylation of η-C8H8Fe(CO)3

X-ray diffraction studies have established the molecular structure of the title compound as involving an unexpected [3.2.1]cyclooctadienylium ligand; the implications of this in terms of chemical reactivity are described.