Elucidation of Structure of the Second Coordination Sphere of Tris(ethylenediamine) Complex by the Isomorphous-Substitution Technique on Solution X-Ray Diffraction

用X射线衍射法测定了三乙二胺铑（Ⅲ）和铬（Ⅲ）配合物的氯化物、溴化物、碘化物、高氯酸盐和硫酸盐的水溶液。根据<Rh>X射线强度数据，以Rh和Cr类质同象替代的方式，导出了Rh原子周围的径向分布函数D^（r）。金属-配体分子内相互作用的计算结果与晶体衍射结果基本一致：r_<Rh-N>=2.08A^^π（n=6）和r_<Rh-c>=2.90-2.95A^^π（n=6）。在3A^^λ之后，在每个D^（r）的3.5-5.0A^^λ区域内，在配体的氨基附近出现了一组独立的峰，这是由于配体的第二配位球相互作用<Rh>。发现这些峰的阴离子依赖性表明存在与氨基接触的阴离子。高氯酸盐溶液在3.5- 5.0 A ^^L范围内的D^<Rh>（r）峰面积小于高氯酸盐溶液的D^（r）峰面积。 ...更多信息 而在5.0-7.5A的范围内，情况相反。这意味着相关的高氯酸根离子存在于亚甲基周围，并且对3.5- 5.0 A ^^H附近的分布没有贡献。因此，<Rh>高氯酸盐溶液的D^（r）峰归因于水合水分子，并通过比较理论曲线进行分析;水分子位于3.90 A ^^π（n=2.5）、4.34 A ^^π（n=4.7）和4.85 A ^^π（n=3.1）。考虑到这一结果，<Rh>分析了溴离子和氯离子溶液的D^（r），证明了在0.3 M和0.9 M溶液中，缔合的溴离子存在于4.64 A ^^（r）（n = 1），氯离子存在于4.50 A ^^（r）（n=1）。这些卤离子被认为是通过取代位于4.34A^位的一个水分子而与氨基接触。从<Rh>碘化物溶液的D^（r）中未获得有意义的结果，因为碘化物的溶解度差导致其浓度低（0.06 M）。硫酸<Rh>盐溶液的D^（r）表明缔合的硫酸根离子以各种取向与氨基接触。少

X-ray diffraction measurements have been carried out for aqueous solutions of chloride, bromide, iodide, perchlorate, and sulfate of tris(ethylenediamine)rhodium(III) and chromium(III) complexes. The radial distribution functions, D^<Rh>(r), around a rhodium atom were derived from the X-ray intensity data in a manner of the isomorphous substitution between Rh and Cr. The following values of metal-ligand intramolecular interactions obtained in this study were almost consistent with the crystarographic results: r_<Rh-N>=2.08A^^ﾟ(n=6) and r_<Rh-c>=2.90-2.95A^^ﾟ(n=6). Beyond 3A^^ﾟ a separated group of peaks attributable to the second coordination-sphere interactions in the vicinity of amino groups of the ligand was appeared in the region of 3.5-5.0A^^ﾟ of each D^<Rh>(r). The anion dependence of these peaks was found to suggest the existence of the anions in contact with the amino group. The peak area in the region of 3.5-5.0A^^ﾟ of D^<Rh>(r) for the perchlorate solution was smaller than th … More at for the chloride solution, while in the region of 5.0-7.5A^^ﾟ the situation was reverse. This means that the associated perchlorate ions exist around the methylene group and do not contribute to the distribution around 3.5-5.0A^^ﾟ. Therefore, the peaks in D^<Rh>(r) of the perchlorate solution were attributed to the hydration water molecules and were and were analyzed by comparing theoretical curves; the water molecules were situated at 3.90A^^ﾟ(n=2.5), 4.34A^^ﾟ(n=4.7), and 4.85A^^ﾟ(n=3.1). Considering this result, D^<Rh>(r) of the bromide and chloride solutions were analyzed and it was proved that the associated bromide ions existed at 4.64A^^ﾟ(n=1) and the chloride ions at 4.50A^^ﾟ(n=1) in both 0.3 M and 0.9 M solutions. These halide ions were considered to be in contact with the amino group by replacing one water molecule situated at 4.34A^^ﾟ. From D^<Rh>(r) of the iodide solution meaningful results were not obtained because of its low concentration(0.06 M) due to poor solubility of the iodide. D^<Rh>(r) of the sulfate solution suggested that the associated sulfate ions were in contact with the amino group with various orientation. Less