Chemistry of cyclopentadienyliron dicarbonyl dimer and ferrocene in zeolite Y cavities: anchoring organometallic fragments into microporous solids

Abstract

The intracavity chemistry of (CpFe(CO){sub 2}){sub 2} (1) and ferrocene in different acid forms of zeolite Y has been studied with EXAFS, in situ FTIR, and TPD-MS spectroscopies. Depending on the stoichiometry of zeolite protons vs the amount of starting complex 1, the complex is either oxidatively cleaved into CpFe(CO){sub 3}{sup +} (2) and CpFe{sup +} coordinated to the zeolite, or protonated to form dimeric (CpFe(CO){sub 2}){sub 2}H{sub +} (3). It is shown that the stability of all complexes is influenced by the intracavity concentration of the zeolite-bridged hydroxyl groups. The cationic monomer 2 is stable up to 500 K in the highly acidic zeolite host, whereas the protonated dimer decomposes above 400 K. At higher temperatures, all carbonyl ligands are split off from the iron complexes, and the remaining dominant fragments are identified as CpFe(OZ){sub n} (n = 2-3), bonded to the zeolite host structure via oxygen coordination. Similar fragments are formed upon thermal decomposition of ferrocene in the zeolite.