Elucidation of optical rotation by X-ray structure analysis of metal complexes

通过金属配合物的 X 射线结构分析阐明旋光性

• 批准号: 07640760
• 负责人: SAKABE Yuzuru
• 金额: $ 0.38万
• 依托单位: School of Science, Kitasato Univrtsity
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640760/
• 关键词: Metal complex; Chirality; Single-crystal X-ray diffraction; Circular dichroism; Optical rotation; 5員キレート環; 配向; 不斉中心; 加成性; S-プロピレンジアミン; R-プロピレンジアミン; クロム錯体; 掌性

(+)_<589>-[Cr(CN)_2(S-pn)(R-pn)]Cl has been prepared as the first metal complex expected to contain a chiral central metal and a pair of enantiomers of bidentate propylenediamines (pn=1,2 diaminopropane=propylenediamine). This compound is specific in their usefulness for elucidating unknown problems related to the correlation among multiple chiralities in its molecule, that is, for solving factors which determine the optical properties such as the optical rotation and circular dichroism of this metal complex. Single crystal X-ray characterization of this compound is essential to the discussions for the above problems. Now, difficulties in confirming the absence of geometric isomers and forming single-crystals have been overcome and such characterization has been carried out. This complex crystallizes in the monoclinic space group P2_1 with a=6.603(4)*, b=18.23(2)*, c=6.606(9)*, beta=114.62(3)^ﾟ, V=722(1)*^3, Z=2, R=0.045, and R_W=0.062 ; the absolute configuration is LAMBDA. The CH-CH_2 bond axis of the S-pn chelate ring is nearly parallel to the dummy three-fold axis of the compound ion, whereas that of the R-pn ring is roughly perpendicular to the same axis (oblique strueture), which enhances its repulsion with the S-pn chelate ring. The CH_3 groups of both chelate rings occupy positions that separate them as much as possible and minimize their repulsion. The following conclusion has been clarified. A fairly accurate additive property is induced among the chiralities generated by the metal and ligands in this metal complex. The chiral contribution of chromium to the molar rotations and the CD spevtra does not depend upon its chelation with pn or en (ethylenediamine). And the contribution of each chirality to the molar rotation of LAMBDA-cis-[Cr(CN)_2(S-pn)(R-pn)]Cl is evaluated.

合成了（+）_<589>-[Cr（CN）_2（S-pn）（R-pn）]Cl，作为第一个含手性中心金属和一对双齿丙二胺（pn= 1，2-丙二胺）对映体的金属配合物。该化合物对于阐明与其分子中的多个手性之间的相关性有关的未知问题，即，对于解决决定该金属络合物的光学性质如旋光和圆二色性的因素是特别有用的。单晶X射线衍射表征是讨论上述问题的基础。现在，确认不存在几何异构体和形成单晶体的困难已经克服，并且已经进行了这种表征。晶体属单斜晶系，空间群P2_1，a=6.603（4）*，B=18.23（2）*，c=6.606（9）*，β =114.62（3）^β，V=722（1）*^3，Z=2，R=0.045，R_W=0.062，绝对构型为LAMBDA。S-pn螯合环的CH-CH_2键轴几乎平行于复合离子的虚拟三重轴，而R-pn螯合环的CH-CH_2键轴则大致垂直于同一轴（斜向结构），这增强了它与S-pn螯合环的排斥作用。两个螯合环的CH_3基团占据尽可能将它们分开并使它们的排斥最小化的位置。以下结论已得到澄清。在该金属配合物中，金属和配体产生的手性之间具有相当精确的加和性。铬对摩尔旋光度和CD spevtra的手性贡献不依赖于它与pn或en（乙二胺）的螯合作用。并计算了各手性对LAMBDA-cis-[Cr（CN）_2（S-pn）（R-pn）]Cl摩尔旋光的贡献。