Intrazeolite organometallics, internal

Intrazeolite organometallics and coordination complexes internal vs. external containment of metal guests... 

The process of loading zeolites with organometallie complexes always brings to the forefront the question of internal versus external confinement of the metal guest. In this paper we present some experiments based on size exclusion, metal loading and intrazeolite chemistry which in conjunction with FT-FAR-IR, EPR and UV-visible reflectance spectroscopy, critically probe the question of internal versus external location for the case of five representative organometallics,... 

Thus by using Co2(C0)8 as a representative organometallic guest, and a combination of size exclusion experiments and intrazeolite oxidation chemistry, as probed through the far-IR cation spectra of sodium and acid faujasites and A-zeolites, one is able to distinguish between internal and external confinement of the metal guest(s) in the zeolite. 

Overall it is quite clear, that a combination of epr spin-probes, UV-vis reflectance spectroscopy, size exclusion and intrazeolite oxidation experiments are able to effectively differentiate those organometallic-zeolite impregnations which place metal guests within the internal voids of the zeolite compared to those on the external surface of the zeolite lattice. 

Intrazeolitic MOCVD chemistry is relatively new. A synthetic chemistry for the preparation of encaged clusters from metd alkyl precursors (alkyl is often methyl) has been suggested by a few researchers. [220, 221] In the first step, a vapor phase precursor is introduced into the zeolite supercages. One of the methyl groups can then react with a Brpnsted add site, thereby produdng CH4 and a concurrent anchoring of the organometallic precursor to the zeolite internal surface (Eq. 4.16, Z represents the zeolite framework). 

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