A Mononuclear Cyclopentadiene–Iron Complex Grafted in the Supercages of HY Zeolite: Synthesis, Structure, and Reactivity

Abstract

The reaction of ferrocene with the acidic hydroxy groups in the supercages of zeolite HY dehydrated at 673 K and the reactivity of the resultant surface species towards CO and O(2) were investigated by temperature-programmed decomposition (TPD) and reduction (TPR) and IR, X-ray absorption fine structure analysis (XAFS), and X-ray photoelectron (XP) spectroscopy. In situ FTIR, TPD, TPR, and chemical analysis reveal that the Cp(2)Fe molecule adsorbed on the zeolite surface loses one cyclopentadienyl group under vacuum at 423 K, which leads to the formation of a well-defined mononuclear surface Fe-C(5)H(6) complex grafted to two acidic sites and one ([triple bond]Si-O-Si[triple bond]) unit, as confirmed by the lack of Fe-Fe contributions in the EXAFS spectra. Each iron atom is coordinated, on average, to three oxygen atoms of the zeolite surface with a Fe--O distance of 2.00 A and to five carbon atoms with a Fe--C distance of 2.09 A. IR spectra indicate that the cyclopentadiene-iron species grafted on the surface of the zeolite is quite stable in vacuo or under an inert or hydrogen atmosphere below 423 K, and is also relatively stable under oxygen at room temperature. However, the cyclopentadiene ligand readily reacts with CO to form a compound containing carbonyl at 323 K, and even at room temperature. The single carbonyl band in the IR spectra provides evidence for the nearly uniform formation of a cyclopentadiene-iron species on the surface of the zeolite.

Remarkable Electrochemical Responses of Ferrocene/NaY Zeolite Composite modified Electrode Based on Hydrophobic Ionic Liquid

“…For the purpose of IR analysis, ferrocene was Soxhlet extracted with ethanol from the Fc/NaY composites. The characteristic adsorption bands of ferrocene extracted are in good agreement with those of bulk ferrocene [22]. These both confirm that ferrocene molecules are encapsulated in the cavities of zeolite Y and preserve their native structures after encapsulation.…”

A Long‐Lived Mononuclear Cyclopentadienyl Ruthenium Complex Grafted onto Anatase TiO2 for Efficient CO2 Photoreduction

“…The preparation of the surface C 5 H 5 ‐RuH complex proceeds by the chemical grafting of ruthenocene ((C 5 H 5 ) 2 Ru) on dehydrated anatase TiO 2 surface, that is, Cp 2 Ru physically adsorbed on anatase TiO 2 reacts with the isolated hydroxyls to remove a Cp group in a CpH way at 423 K. The remnant C 5 H 5 ‐Ru fragment is chemically bonded to surface hydroxyl sites of TiO 2 nanoparticles via the Ti‐O‐Ru linkage. FTIR spectra (Figure A) clearly display several characteristic IR bands at 1524, 1445, and 1412 cm −1 corresponding to the C 5 H 5 ligand of the surface Ru complex, indicating that the chemical grafting of Cp 2 Ru to anatase TiO 2 nanoparticles is basically in coincidence with those of Cp 2 Ni and Cp 2 Fe reported in our previous work ,. The different point is the occurrence of two weak IR bands at 2071 and 2002 cm −1 belonging to the stretching vibration of Ru−H bonds .…”

Self-organization of extraframework cations in zeolites

“…For example, chemical vapour deposition of trimethyl gallium (Ga(CH 3 ) 3 ) onto the acidic form of high-silica ZSM-5 zeolite yields well-defined dispersed Ga(CH 3 ) + 2 species compensating the negative charge of the zeolite framework (Hensen et al 2005(Hensen et al , 2007. A similar procedure has been used for introducing well-defined Fe (Long et al 2007) and Zn (Almutairi et al 2012) precursors into zeolites by reacting ferrocene and dimethylzinc, respectively, with zeolitic Brønsted acid sites. The grafted organometallic precursors are then decomposed to produce the desired well-defined catalytic species.…”