Institute of Physics, Ilmenau University of Technology , P.O. Box 100565, 98684 Ilmenau, Germany.
J Phys Chem A. 2014 Feb 6;118(5):862-71. doi: 10.1021/jp411033h. Epub 2014 Jan 28.
The individual absorption spectra of the two NH tautomers of 10-(4,6-dichloropyrimidin-5-yl)-5,15-dimesitylcorrole are assigned on the basis of the Gouterman four-orbital model and a quantum chemical TD-DFT study. The assignment indicates that the red-shifted T1 tautomer is the one with protonated pyrrole nitrogen atoms N(21), N(22) and N(23), whereas the blue-shifted T2 tautomer has pyrrole nitrogen atoms N(21), N(22) and N(24) protonated. A wave-like nonplanar distortion of the macrocycle in the ground state is found for both NH tautomers, with the wave axis going through the pyrroles containing N(22) and N(24). The 7C plane determined by the least-squares distances to the carbon atoms C1, C4, C5, C6, C9, C16, and C19 is suggested as a mean corrole macrocycle plane for the analysis of out-of-plane distortions. The magnitude of these distortions is distinctly different for the two NH tautomers, leading to substantial perturbations of their acid-base properties, which are rationalized by the interplay of the degree of out-of-plane distortion of the macrocycle as a whole and the tendency of the pyrrole nitrogen atoms toward pyramidalization, with the former leading to a basicity increase whereas the latter enhances the acidity.
两种互变异构体的个体吸收光谱 10-(4,6-二氯嘧啶-5-基)-5,15-二-间甲苯基-卟啉基于 Gouterman 四轨道模型和量子化学 TD-DFT 研究进行了分配。分配表明，红移 T1 互变异构体是吡咯氮原子 N(21)、N(22)和 N(23)质子化的互变异构体，而蓝移 T2 互变异构体具有吡咯氮原子 N(21)、N(22)和 N(24)质子化。在基态下，两种 NH 互变异构体都发现了大环的波状非平面扭曲，波轴穿过含有 N(22)和 N(24)的吡咯。通过到碳原子 C1、C4、C5、C6、C9、C16 和 C19 的最小二乘距离确定的 7C 平面被建议作为分析面外扭曲的卟啉大环平面。这两种 NH 互变异构体的这些扭曲的幅度明显不同，导致它们的酸碱性质发生了实质性的变化，这可以通过大环整体的面外扭曲程度与吡咯氮原子的三角化倾向之间的相互作用来合理化，前者导致碱性增加，而后者增强了酸度。
