Ligand substitution and nucleophilic reactivity of tricarbonyl(1-3:5,6η-cyclooctadienylium)iron cation and its derivatives

Abstract

The tricarbonyl(1-3:5,6-η-cyclooctadienylium)iron cation (I) undergoes attack by triphenylphosphine at two different sites, on the organic group or at the metal; the first type of attack leads to a phosphonium ion and the second case to a dicarbonyl(1-3:5,6-η-cyclooctadienylium)triphenylphosphineiron cation. The two products have been isolated and identified by IR spectroscopy. The reaction between cation I and iodide ion can also involve attack on the organic group or the metal, giving rise to tricarbonyl[4-6-η,1-σ-(2-iodocyclooctenyl)]iron and dicarbonyl(1-3:5,6-η-cyclooctadienylium)iodoiron, respectively. Only the latter has been isolated and characterized; for the former indirect evidence is available, involving its reactions with CN − and PPh 3. The reactions between cation I and the various nucleophiles OMe −, N − 3, CN −, and AsPh 3 and those between its iodo derivative and PPh 3 and AsPh 3 were also studied.