Mechanism of the Substitution Reaction of Technetium Bata-Diketone Complexes.

锝配合物在配位化学和放射性药物研究领域具有广泛的应用前景。由于锝中不存在稳定同位素，从废液中回收放射性锝是一个亟待解决的问题。本研究正是从这些角度进行的.三（乙酰丙酮）锝（III）是取代基惰性的碱水解，在碱性溶液中，甚至在室温下。建立了碱水解反应机理.初步研究表明，在强酸存在下，三（乙酰丙酮）锝（III）中的配体分子被乙腈取代。溶剂取代反应在30 ° C下以8.86 × 10 ~ 4·s ~（-1）的速率得到双（乙腈）双（乙酰丙酮）锝（III）<-4><-1>。通过红外光谱和元素分析对配合物的结构进行了鉴定.通过六硫脲合锝（III）离子与EDTA的配体取代反应，阐明了锝（III）-EDTA络合物的形成机理.建立了在阴离子交换柱上从含其它金属离子的放射性废液中富集分离锝的方法。用TBP作萃取剂，考察了用高氯酸溶液从柱上洗脱的高锝酸根离子的浓缩过程。以四氯化碳或环己烷为稀释剂，研究了酸浓度和TBP浓度对高锝酸盐分配比的影响。

Technetiumu complexes have been interested in the field of the coordination chemistry and radiopharmaceuticals. Since no stable isotopes exist in technetium, the serious problem that radioactive technetium is recovered from waste solution should be solved as an urgent project. The present studies have been carried out from these view points.1. Tris (acetylacetonato) technetium (III) which is substituion-inert is base-hydrolyzed in an alkaline solution even at room temperature. The reaction mechanism of base-hydrolysis has been established.2. A preliminary research showed that a ligand molecule in tris (acetylacetonato) technetium (III) is replaced by acetonitrile in the presence of a strong acid. The solvent substitution reaction gives bis (acetonitrile) bis (acetylacetonato) technetium (III) with a rate of 8.86 x10^<-4> s^<-1> at 30^ﾟC. The complex was isolated as perchlorate, of which identification was done by means of IR spectroscopy and elemental analysis.3. The mechanism of the formation reaction of technetium (III) -EDTA complex was clarified by the ligand substitution reaction of hexakis (thioureato) technetium (III) ion with EDTA.4. The concentration and separation of technetium from the radioactive waste solution containing other metal ions was established on an anion-exchange column. Furthermore, the concentration process of pertechnetate ion eluted with a perchloric acid solution from the column was examined by means of solvent extraction using TBP. Dependence of the concentration of acid and TBP on the distribution ratio of pertechnetate was studied using carbon tetrachloride or cyclohexane as a diluent.