Nemykin Victor N, Barrett Christopher D, Hadt Ryan G, Subbotin Roman I, Maximov Alexander Y, Polshin Ernst V, Koposov Alexey Y
Department of Chemistry and Biochemistry, University of Minnesota Duluth, 1039 University Drive, Duluth, MN 55812, USA.
Dalton Trans. 2007 Aug 21(31):3378-89. doi: 10.1039/b703581k. Epub 2007 Jun 4.
Metal-free 5,10,15,20-tetraferrocenylporphyrin and 5,10-bisferrocenyl-15,20-bisphenylporphyrin have been prepared and characterized by UV-Vis, MCD, (1)H, (13)C, and variable-temperature NMR, APCI- and ESI-MS, and Mössbauer spectroscopy, while their redox properties were investigated using electrochemical (cyclic voltammetry and differential pulse voltammetry), spectroelectrochemical, and chemical oxidation approaches. The electronic structure calculations at Density Functional Theory level reveal that both compounds adopt saddle conformations and the HOMOs in both complexes are predominantly metal-centered, while the LUMOs predominantly consist of porphyrin pi* orbitals. In spite of the rotational freedom of ferrocenyl substituents at room temperature, both metal-free 5,10,15,20-tetraferrocenylporphyrin and 5,10-bisferrocenyl-15,20-bisphenylporphyrin are able to form mixed-valence states upon the successive ferrocene-based two- and one-electron oxidations, respectively, as confirmed by UV-Vis, MCD, Mössbauer, electro-, and spectroelectrochemical methods, and thus, the earlier suggested (Boyd et al. Chem. Commun., 1999, 637) requirements for the formation of mixed-valence states in ferrocene-containing porphyrins should be revised.
已制备出无金属的5,10,15,20-四二茂铁基卟啉和5,10-双二茂铁基-15,20-双苯基卟啉，并通过紫外可见光谱、磁圆二色光谱、¹H、¹³C和变温核磁共振、大气压化学电离和电喷雾电离质谱以及穆斯堡尔光谱对其进行了表征，同时使用电化学方法（循环伏安法和差分脉冲伏安法）、光谱电化学方法和化学氧化方法研究了它们的氧化还原性质。密度泛函理论水平的电子结构计算表明，这两种化合物均采用鞍形构象，且两种配合物中的最高占据分子轨道主要以金属为中心，而最低未占分子轨道主要由卟啉π*轨道组成。尽管二茂铁基取代基在室温下具有旋转自由度，但通过紫外可见光谱、磁圆二色光谱、穆斯堡尔光谱、电化学和光谱电化学方法证实，无金属的5,10,15,20-四二茂铁基卟啉和5,10-双二茂铁基-15,20-双苯基卟啉在基于二茂铁的连续双电子和单电子氧化后分别能够形成混合价态，因此，之前提出的（博伊德等人，《化学通讯》，1999年，637页）含二茂铁卟啉中形成混合价态的条件应该修正。
