1998 Fiscal Year Final Research Report Summary
A Relation between Rate Constant for the Ligand Substitution and Substitution Reactivity in the Technetium and Rhenium Complexes
| Project/Area Number |
08640708
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic chemistry
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| Research Institution | Shizuoka University |
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Principal Investigator |
OMORI Takashi Shizuoka University, Faculty of Science, Professor, 理学部, 教授 (80004349)
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| Project Period (FY) |
1996 – 1998
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| Keywords | technetium / rhenium / technetium-nitrido complexes / thiourea complexes / ligand substitution reaction / tris (1,10-phenanthrorine) iron (II) / mechanism of solvent extraction / base hydrolysis |
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| Research Abstract |
The ligand substitution of the complexes of technetium and rhenium was kinetically investigated based on the syntheses of radiopharmaceuticals labeled with technetium and rhenium radioisotopes.
In the synthesis of technetium complex, photometric determination of technetium is required. All the methods proposed included the process of reduction of pertechnetate and ligand substitution. Consequently, a new and simple method for the spectrophotometric determination of technetium has been developed by means of the solvent extraction of tris(1,10-phenanthroline)iron(II) with pertechnetate into nitrobenzene. Mechanism of hydrolysis of tetrachloronitridotechnetate(VI) was established by means of the solvent extraction with tetrachloroarsonium chloride(TPAC). In the presence of 3,5-dichlorophenol in the organic phase, no trans-effect of Tc*N bond in tetrachloronitridotechnetate( VI) was found. No synergestic effect can be explained by the formation of an ion pair of TPAC and DCP.Kinetic investigation of the base hydrolysis of bis(acetylacetonato)nitridotechnetium(V) was done in an acetonitrile solution, showing that the replacement of an acetonitrile for the acetylacetonate was followed by the attack of hydroxide ion. Finally the acetylacetonate complex was fully decomplsed by the base hydrolysis and the rate constants for these complicated processes were determined. Formation mechanism of hexakis(thiourea derivative)technetium(III) ion from pertechnetate was studied kinetically using thiourea, dimethylthiourea and diethylthiourea. The reaction of hexakis(thiourea)technetium(III) ion with dietylenetriaminepentaacetic acid (DTPA) was also studied kinetically. Base hydrolysis of hexakis(thiourea)rhenium(III) was compared with that of hexakis(thiourea)technetium(III). On the basis of these results, the substitution reactions of technetium complexes was reviewed at the First Russian-Japanese Seminar on Technetium held in Moscow, 1996.
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