Institute of Problems of Chemical Physics RAS , Chernogolovka, Moscow Region, 142432 Russia.
Institute of Solid State Physics RAS , Chernogolovka, Moscow Region, 142432 Russia.
J Org Chem. 2018 Feb 16;83(4):1861-1866. doi: 10.1021/acs.joc.7b02791. Epub 2018 Jan 30.
A crystalline {cryptand2.2.2.}{HT(4-Py)P}·CHCl (1) salt with tetra(4-pyridyl)porphyrin radical anions was obtained, enabling the effect of reduction on a metal-free porphyrin macrocycle to be studied. In contrast to pristine HT(4-Py)P, the HT(4-Py)P radical anions have altered C-C(meso) bonds due to partial loss of aromaticity from the porphyrin macrocycle. Short and long bonds have average lengths of 1.396(3) and 1.426(3) Å, which thus differ by 0.03 Å. Reduction affects the positions of the Soret and Q-bands of porphyrin observed in the spectrum of 1 at 439 and 512, 583, and 614 nm, and new bands of the radical anion appear at 684, 755, and 900 nm. The HT(4-Py)P radical anions have a spin state of S = 1/2 and a magnetic moment of 1.64 μ at 300 K. Salt 1 shows a narrow asymmetric EPR signal fitted with two Lorentzian lines, with g = 2.0031 and a line width (ΔH) of 0.186 mT, and g = 2.0019 (ΔH = 0.284 mT) at 295 K, and this signal splits into three components below 39 K. Salt 1 shows antiferromagnetic spin coupling with a Weiss temperature of -2 K.
一种含有四(4-吡啶基)卟啉自由基阴离子的[2.2.2]cryptand（K）HT(4-Py)P·CHCl（1）盐被合成，这使得研究无金属卟啉大环的还原效应成为可能。与原始的 HT(4-Py)P 相比，HT(4-Py)P 自由基阴离子由于卟啉大环的部分芳香性丧失，导致 C-C(meso)键发生了改变。短键和长键的平均长度分别为 1.396(3)Å 和 1.426(3)Å，相差 0.03Å。还原作用影响了在 1 的光谱中观察到的卟啉的 Soret 和 Q 带的位置，它们分别位于 439 和 512、583 和 614nm，而自由基阴离子的新带出现在 684、755 和 900nm。HT(4-Py)P 自由基阴离子的自旋态为 S = 1/2，在 300 K 时的磁矩为 1.64μ。盐 1 显示出一个窄不对称的 EPR 信号，拟合为两条洛伦兹线，g = 2.0031，线宽（ΔH）为 0.186 mT，g = 2.0019（ΔH = 0.284 mT）在 295 K，低于 39 K 时该信号分裂为三个分量。盐 1 表现出反铁磁自旋耦合，Weiss 温度为-2 K。
