Intrazeolite half-sandwich complexes of rhodium and iridium: Spectroscopy and reactivity patterns

Journal Article · Thu Sep 07 00:00:00 EDT 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100355a029· OSTI ID:7171330

Ozin, G A; Haddleton, D M; Gil, C J ^[1]

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1. Univ. of Toronto, Ontario (Canada)

The incorporation of the half-sandwich complexes CpM(CO){sub 2}, Cp*M(CO){sub 2}, and CpM(C{sub 2}M{sub 4}){sub 2} (M = Rh, Ir; Cp = C{sub 5}H{sub 5}; Cp* = (CH{sub 3}){sub 5}C{sub 5}), as well as CpRh(C{sub 2}H{sub 4})CO and (acac)Rh(CO){sub 2}, into zeolites has been investigated. Initial studies have focused on the immobilization and characterization of the species, primarily in alkali-metal Y zeolites, through in situ optical reflectance and vibrational spectroscopy. Size exclusion studies in Na{sub 12}-A (4.2 {angstrom}) and K{sub 8}Na{sub 4}-A (3.4 {angstrom}) zeolites demonstrate internal rather than external confinement of the organometallic. Two distinct anchoring sites within the supercages are observed for the carbonyl systems. Site 1 interaction is attributed to a cation-ring coordination, while site 2 is assigned to a single cation interaction with the oxygen atoms of both carbonyl ligands. The population distribution between sites 1 and 2 varies with the nature of the organometallic guest, the exchanged cation, and the Si:Al ratio of the zeolite. The {sup 13}CO exchange reactions of encapsulated CpM(CO){sub 2} and Cp*M(CO){sub 2} show faster rates compared to solution-phase work in those alkali-metal Y zeolites that exhibit population of both sites 1 and 2. Preliminary studies indicate {sup 13}CO pressure dependent exchange kinetics for CpIr(CO){sub 2} in K-Y zeolite. This has been attributed to an intrazeolite associative exchange mechanism which is enhanced by site 1 occupation. Similarly, fast room temperature CO substitution of ethylene from intrazeolite CpM(C{sub 2}H{sub 4}){sub 2} yields the dicarbonyl in the same sites and distributions as encountered for a freshly CpM(CO){sub 2} impregnated sample. The thermal properties of the entrapped organometallics have also been probed and the anchored half-sandwich products, CpM and Cp*M, tentatively identified.

• OSTI ID: 7171330
• Journal Information: Journal of Physical Chemistry; (USA), Vol. 93:18; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ZEOLITES
REACTIVITY
SPECTROSCOPY
CARBON MONOXIDE
CATALYSTS
DATA ANALYSIS
EXPERIMENTAL DATA
IRIDIUM
MEASURING INSTRUMENTS
MEASURING METHODS
RHODIUM
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DATA
ELEMENTS
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
METALS
MINERALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
TRANSITION ELEMENTS
360603* - Materials- Properties
400000 - Chemistry
400201 - Chemical & Physicochemical Properties