1994 Fiscal Year Final Research Report Summary
A Time-resolved Infrared Study of Photocatalysis for C-H Activation
| Project/Area Number |
05640670
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
物質変換
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| Research Institution | Department of Chemistry, School of Science, Kitasato University |
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Principal Investigator |
OHISHI Shigero Kitasato Univ.School of Sci.Professor, 理学部・化学科, 教授 (80213619)
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| Project Period (FY) |
1993 – 1994
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| Keywords | time-resolved infrared spectroscopy / Vaska-type complex / quantum yield |
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| Research Abstract |
A system for time-resolved infrared spectroscopy was established. The optical system of EPI-G2 (HITACHI) infrared spectrometer was basically used except that an MCT element was employed as a detector and that the width of slits was fixed to 1mm. Sample solutions in a water-cooled CaF_2 cell (0.5mm in optical path length) were laser-photolyzed every 6s by the harmonic of Nd : YAG laser with an energy lower than 20mJ per pulse, and were renewed for every laser pulse by a computer controlled electric valve. The system is reliable and more economical as compared with using infrared laser as an infrared source.
In order to establish a standard for actinometry with monitoring infrared, an extinction coefficient for ketene intermediate at 2135cm^<-1> was determined as 2300 M^<-1>cm^<-1>. The ketene transient was generated by the laserphotolysis of o-diazonaphthoquinone.
Vaska-type complexes of rhodium, which were reportedly effective in photocatalytic C-H activation, were investigated for their initial photoreactions. Triphenylphosphine, tritolylphosphine, and diphenylmethylphosphine were used as ligands in the complex. It was found that the photoelimination of carbonyl, rather than a phosphine ligand, occurred with the quantum yield of 0.1, and that the resulted ClRh (phosphine) _2 attacked mainly to the parent ClRh (CO) (phosphine) _2 to give a binuclear rhodium complex. Therefore, very low values were estimate for quantum yields of photocatalytic C.H activation by these complexes. The complex of trimethylphosphine is planned to be investigated.
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