THE PHOTOCHEMISTRY AND PHOTOCATALYTIC REACTIONS OF IRON CARBONYLS ADSORBED ONTO POROUS VYCOR GLASS.
Item
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Title
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THE PHOTOCHEMISTRY AND PHOTOCATALYTIC REACTIONS OF IRON CARBONYLS ADSORBED ONTO POROUS VYCOR GLASS.
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Identifier
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AAI8614668
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identifier
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8614668
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Creator
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DARSILLO, MICHAEL STEVEN.
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Contributor
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Harry D. Gafney
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Date
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1986
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Inorganic
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Abstract
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Fe(CO)(,5) and Fe(,3)(CO)(,12) physisorb onto PVG without significant change in their electronic or vibrational spectra, however, Fe(,2)(CO)(,9) undergoes disproportionation upon adsorption to yield Fe(CO)(,5) and Fe(CO)(,12). UV photolysis of Fe(CO)(,5)(ads) in vacuo leads to formation of the tetracarbonyl with a quantum yield of unity. The tetracarbonyl rapidly reacts with the PVG surface and chemisorbed water to form the spectrally distinct, oxidative addition products H-Fe(CO)(,4)-OSi and H-Fe(CO)(,4)-OH. These primary photoproducts undergo secondary photolysis to form, depending on the initial loading, either elemental iron or the trimeric cluster, Fe(,3)(CO)(,12). Diffuse reflectance FTIR spectroscopy, recorded after cw or pulsed laser excitation, established the presence of dimeric and trimeric intermediates. Trapping experiments with CO and trimethylphosphine indicate a photochemically driven, stepwise reaction sequence in which the intermediates leading to cluster formation are more highly unsaturated intermediates, principally Fe(CO)(,3).;Diffuse reflectance FTIR spectra, recorded after cw excitation of Fe(CO)(,5)(ads) under 100 torr of olefin, establish the presence of a host of monomeric and dimeric catalytically active iron carbonyl-olefin complexes. The photocatalyzed isomerization of 1-pentene by the Fe(CO)(,5)-PVG hybrid system occurs with a quantum yield of 155 (+OR-) 2.0, indicating photogeneration of species which are extremely efficient alkene isomerization catalysts at ambient temperature. The trans/cis ratio for the reaction differs from that found in fluid solution and is similar to the product distribution observed for iron carbonyl complexes containing bulky ligands in their coordination sphere.;UV photolysis of Fe(,3)(CO)(,12)(ads) results in CO evolution along with H(,2) and CH(,4) evolution. Periodic analysis of the gaseous effluent surrounding the photolyzed sample, in conjunction with spectral analysis, indicate that CH(,4) evolution is mediated by an irreversibly oxidized iron species. The formation of photoinduced high resolution optical density changes using the Fe(CO)(,5)-PVG system has also been investigated.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Chemistry
