Reactions of the 'ferrole' complex [Fe-2(CO)(6)(C(2)Et(2))(2)] with Group 15 donor ligands and with alkynes. Stepwise formation and disengagement of tropones. Crystal and molecular structure of [Fe-2(CO)(5){(CEt)(2)CO(CEt)(2)CHCPh}]

The reactions of [Fe-2(CO)(6)(C(2)Et(2))(2)] (complex A) with phosphorus donors in the presence of Me,NO results in an unexpected CO insertion to give 'flyover-bridged' dinuclear compounds. The same reaction also takes place with nitriles giving similar, though less stable, complexes. The reactions of A with terminal alkynes give rise again to CO insertion into the ferrole ring and, in addition, the entering alkyne forms C-C bonds with the flyover moiety. The structure of [Fe-2(CO)(5){(CEt)(2)CO(CEt)(2)CHCPh}] has been fully elucidated by an X-ray study. Several organic products, including tropones, are produced by displacement reactions of the organic moieties from the ferrole and flyover derivatives, under thermal conditions.