Reaction of Silyl radicals within a Porphyrin π-Cloud

合成了一系列轴向含有烷基、烯基、芳基和炔基的有机硅卟啉化合物。在可见光照射下，二烷基硅卟啉与硝基氧基化合物如克里思反应，得到二硝基氧基硅卟啉。在没有硝酰化合物存在的情况下，光解导致形成长寿命（在25℃下>50天）的EPR活性硅双自由基，g值为2.0026，其在黑暗中不与硝酰化合物反应，但在可见光激发下被克里思顺利捕获，得到二硝酰硅复合物。在自由硝氧基化合物的存在下，用可见光照射二硝氧基硅导致可逆的轴向配体交换，其响应于光的开关而进行，以达到平衡。

A series of organosilicon porphyrins) with alkyl (sp^3), alkenyl, aryl (sp^2), and alkynyl (sp), groups at the axial positions were synthesized. Upon irradiation with visible light, dialkylsilicon porphyrins reacted with nitroxy compounds, such as TEMPO to give dinitroxysilicon porphyrins. In the absence of nitroxy compounds, photolysis resulted in the formation of a long-lived (>50 days at 25℃) EPR-active silicon diradical with a g-value of 2.0026, which did not react with nitroxy compounds in the dark but was smoothly trapped by TEMPO to give dinitroxysilicon complex upon excitation with visible light. Irradiation of the dinitroxysilicon with visible light in the presence of free nitroxy compoundss resulted in reversible axial ligand exchange, which proceeded in response to the switching-on and-off of the light, to reach an equilibrium.