Sudies on Structural Chemistry of Neptunyl Complexes by ^<237>Np Mossbauer spectroscopy.

通过^<237>Np穆斯堡尔光谱研究海王基配合物的结构化学。

• 批准号: 15550056
• 负责人: TAKEDA Masuo
• 金额: $ 2.43万
• 依托单位: Toho University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15550056/
• 关键词: ^<237>Np Mossbauer spectroscopy; neptunyl(VI) complex; chemical bonding; uranyl(VI) complex; nitrogen-ligating ligand; pyridine complex; Schiff base complex; macrocvclic complex; ウラニル(VI)錯体; アセチルアセトン錯体; ネプツニウム; メスバウアー分光; ビピリジン錯体; ^<237>Np

The aim of this research is to obtain the information on the chemical bonding in the actinide compounds through the ^<237>Np Mossbauer spectroscopic study of neptunyl(VI) complexes containing nitrogen-containing ligands. Mossbauer parameters of the pyridine complex [NpO_2(acac)_2py] and the oxalate NpC_2O_4・3H_2O, both having the pentagonal bipyramidal structure, are compared. The value of isomer shift of [NpO_2(acac)_2py] having a nitrogen donor atom is larger than that of NpC_2O_4・3H_2O, suggesting that the nitrogen atom donates more electrons to the Np 5f orbitals than the oxygen atoms do. The isomer shift of [NpO_2(NO_3)_2(2,2'-bpy)] is larger than that of [NpO_2(acac)_2py], indicating that the increase in the coordination number from 7 (the latter) to 8 (the former) causes the decrease in the contribution of 7s electron. These results show that the electrons from the coordinating nitrogen atom are donated to 5f orbitals rather than 7s one, being in good contrast to the lanthanide complexes where the electrons are directly accommodated in 6s orbital.Synthetic investigations are also carried out to develop the nitrogen-ligating actinyl(VI) complexes using uranyl(VI) in order to strengthen the Mossbauer spectroscopic data. Several [UO_2(acac)py] derivatives, [UO_2(acac)(4-R-py)] (R=Me,Et,'Bu,CN,Cl,NMe_2) are prepared and their structures are determined. A good correlation between U-N and U=O distances are observed. Six macrocyclic N_6-coordinating Schiff base UO_2 complexes derived from pyrroledicarboaldehyde and diamines are prepared and two of the structurally characterized. Four acyclic Schiff base UO_2 complexes including a heterobinuclear Cu^<2+>-UO_2 complex are also obtained and their structures are determined.

本研究的目的是通过<237>对含氮配体的镎基（VI）配合物的~ 1 Np穆斯堡尔谱学研究，获得锕系化合物中化学键的信息。本文比较了具有五角双锥结构的吡啶配合物[NpO_2（acac）_2py]和草酸盐NpC_2O_4·3H_2O的穆斯堡尔参数。含氮原子的[NpO_2（acac）_2py]的同分异构位移值大于NpC_2O_4·3H_2O，说明氮原子比氧原子向Np 5 f轨道提供更多的电子。[NpO_2（NO_3）_2]的同分异构位移（2，2 '-bpy）]的配位数比[NpO_2（acac）_2py]的配位数大，说明配合物的配位数从7（后者）至8结果表明，配位氮原子的电子被贡献给5 f轨道而不是7s轨道，与镧系元素配合物中电子直接容纳在6s轨道上的情况形成了很好的对比.为了加强穆斯堡尔谱数据，我们还进行了合成研究，发展了以铀酰（VI）为配体的氮配位锕基（VI）配合物.合成了几种[UO_2（acac）py]衍生物[UO_2（acac）（4-R-py）]（R=Me，Et，'Bu，CN，Cl，NMe_2），并测定了它们的结构。观察到U-N和U=O距离之间的良好相关性。合成了六个由吡咯二甲醛和二胺衍生的大环N_6配位Schiff碱UO_2配合物，并对其中两个配合物进行了结构表征。还得到了四个非环状Schiff碱UO_2配合物，其中包括一个异双核Cu^&lt;2+&gt;-UO_2配合物，并确定了它们的结构。