Synthesis and isolation of stable cation radicals of triarylphosphines, and development to functional molecules

开发了性能优良的三芳基膦稠环化合物。合成了三（2，4，6-三环己基苯基）膦，用亚硝鎓盐氧化得到了相应的阳离子自由基，并首次将其作为三芳基膦的阳离子自由基分离得到紫色晶体。X射线晶体学揭示了磷的平面结构和各向异性的氢氟碳化物常数从EPR谱的角度依赖的单晶。合成了2，6-二烷基苯基、2，6-二芳基苯基、2-烷基-6-芳基苯基等多芳基拥挤三芳基膦，并对其结构、动力学立体化学，特别是膦的反转势垒以及由磷原子上的三个芳环组成的螺旋桨的螺旋性引起的异构体间的相互转化进行了详细的研究。拥挤的三芳基膦部分和其他功能位点之间的分子内相互作用也进行了研究。合成了几种在磷的4位上带有给体或受体的三芳基膦，研究了取代基对电子光谱的影响。发现诸如甲酰基的吸电子基团引起最长吸收波长的红移，从而使红色膦变成橙子。通过Suzuki偶联反应合成了含醌的三芳基膦杂环化合物，系统地研究了它们的氧化还原性质与分子内电荷转移的关系。（4-溴-2，6-二环己基苯基）双（2，4，6-三环己基苯基）膦是合成拥挤的三芳基膦的关键中间体，可被氧化成可分离的阳离子自由基并具有功能位。合成了带有两个拥挤的三芳基膦部分的双膦，它们通过联苯、偶氮和硝酰基键连接。

Crowded triarylphosphines of advanced properties were developed. One of the most crowded triarylphosphines, tris(2,4,6-tricyclohexylphenyl)phosphine was synthesized and the corresponding cation radical was prepared by oxidation with nitrosonium salts and isolated as purple crystals for the first time as a cation radical of triarylphosphine. X-ray crystallography revealed planar structure of phosphorus and anisotropic hfc constants were obtained from angular dependence of EPR spectra of a single crystal. Several crowded triarylphosphines carrying various aryl groups such as 2,6-dialkylphenyl, 2,6-diarylphenyl, and 2-alkyl-6-arylphenyl groups were synthesized and detailed structure, dynamic stereochemistry, especially inversion barrier of the phosphine and interconversion of isomers arising from helicity of propeller composed of three aromatic rings attached to the phosphorus atom. Intramolecular interaction between the crowded triarylphosphine moiety and the other functional site was also investigated. Several triarylphosphines carrying a donar or an acceptor at the 4-position to the phosphorus were synthesized and the substituent effects on electronic spectra were studied. Electron withdrawing groups such as a formyl group were found to cause red shift of the longest absorption wavelength to give orange to red colored phosphines. Crowded triarylphosphines carrying quinones were synthesized by Suzuki coupling and relation between redox properties and intramolecular charge transfer was systematically clarified. (4-Bromo-2,6-dicyclohexylphenyl)bis(2,4,6-tricyclohexylphenyl)phosphine was developed as a key synthetic intermediate for crowded triarylphosphines which can be oxidized to isolable cation radicals as well as possess functional sites. Diphosphines carrying the two crowded triarylphosphine moieties connected by biphenyl, azo, and nitroxyl linkage were synthesized.