取代铁卟啉的拉曼及红外光谱分析

Raman and IR Spectroscopic Analysis of Substituted Tetraphenylporphyrin Iron Complexes

合成了系列取代铁卟啉化合物,研究了拉曼光谱及红外光谱。对二价铁卟啉RTPPFe(Ⅱ)和三价铁卟啉RTPPFeCl(Ⅲ)的红外光谱和拉曼光谱进行了对比分析,结果表明,二价铁卟啉在常温下是不稳定的,通常在其轴向位置上吸附氧分子而形成铁卟啉的超氧化物RTPPFe-O2,其稳定的立体构型为end-on式结构。采用量化软件对化合物的分子结构进行了模拟,得出了其分子结构参数,并结合化合物的红外及拉曼光谱,研究了分子结构对波谱位移的影响。不同结构的二价铁卟啉RTPPFe-O2拉曼及红外吸收峰的位置发生了不同程度的位移,其位移情况与分子的扭曲程度有关,即RTPPFe-O2的Fe-O2特征拉曼吸收峰以及红外特征吸收峰(Fe—O)的位置随着Fe—O—O角的增大而向高波数移动。

In the present paper, two series of substituted tetraphenylporphyrin iron compounds RTPPFe（ Ⅱ） and RTPPFeCI （Ⅲ ） were synthesized by two-step synthetic method. Raman and IR spectra of tetraphenylporphyrin iron complexes were investigated. By analyzing the IR and Raman spectra of RTPPFe（Ⅱ ） and RTPPFe（ Ⅲ）Cl, it was confirmed that the RTPPFe（ Ⅱ ） complexes were usually unstable at normal temperature and existed via the coordination of dioxygen with the iron （ Ⅱ ） center, i. e. they formed into TPPFe-O2, and the stable configuration of dioxygen with the iron （ Ⅱ） center was ＂end-on＂. In addition, the geometric structure optimization of substituted iron tetraphenylporphyrin complexes was performed by PM3 semi-empirical and MM＋ method quantum calculation. The structure parameters were obtained, including EHOMO, ELUMO and total energy, bond length of Fe-Cl etc. The effect of molecular structure on vibrational frequency shift was studied by combing the IR and Rarnan spectra. The results showed that for iron tetraphenylporphyrins （RTPPFe-Oe） with different structure, the vibrational frequencies of the Fe-O bond were associated with their twist degree of molecular structures, i.e. the Raman and IR characterization vibrational frequencies of the Fe-O2 were up shifted with the increase in the Fe-O-O angle of iron tetraphenylporphyrins （RTPPFe-O2 ）molecule.