Positional Isomers of Isocyanoazulenes as Axial Ligands Coordinated to Ruthenium(II) Tetraphenylporphyrin: Fine-Tuning Redox and Optical Profiles
Positional Isomers of Isocyanoazulenes as Axial Ligands Coordinated to Ruthenium(II) Tetraphenylporphyrin: Fine-Tuning Redox and Optical Profiles
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DOI：
10.1021/acs.inorgchem.9b01030
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发表时间：
2019-07-15
影响因子：
4.6
通讯作者：
Nemykin, Victor N.
中科院分区：
文献类型：
--
作者：
Fathi-Rasekh, Mahtab;Rohde, Gregory T.;Nemykin, Victor N.
两个同分异构的钌（II）/5，10，15，20-四苯基卟啉配合物具有轴向配位的氧化还原活性，低光学带隙的2-或6-异氰基奥基配体已被分离和表征的NMR，UV-vis，和磁性圆二色性（MCD）光谱方法，高分辨率质谱，和单晶X-射线晶体学。紫外-可见光谱和MCD光谱支持卟啉发色团的Q带区域中存在低能的、以甘菊环为中心的跃迁。新的L2 RuTPP配合物中的第一配位球反映了压缩的四面体几何结构。通过电化学和光谱电化学方法评估了新化合物的氧化还原性质，并与密度泛函理论和CASSCF计算预测的电子结构相关。实验和理论数据都与涉及轴向azulenic配体的前两个还原过程一致，而氧化曲线（在增加电位的方向上）由钌离子、卟啉核和轴向azulenic部分施加。
Two isomeric ruthenium(II)/5,10,15,20-tetraphe-nylporphyrin complexes featuring axially coordinated redox-active, low-optical gap 2- or 6-isocyanoazulene ligands have been isolated and characterized by NMR, UV-vis, and magnetic circular dichroism (MCD) spectroscopic methods, high-resolution mass spectrometry, and single-crystal X-ray crystallography. The UV-vis and MCD spectra support the presence of the low-energy, azulene-centered transitions in the Q band region of the porphyrin chromophore. The first coordination sphere in new L2RuTPP complexes reflects compressed tetragonal geometry. The redox properties of the new compounds were assessed by electrochemical and spectroelectrochemical means and correlated with the electronic structures predicted by density functional theory and CASSCF calculations. Both experimental and theoretical data are consistent with the first two reduction processes involving the axial azulenic ligands, whereas the oxidation profile (in the direction of increasing potential) is exerted by the ruthenium ion, the porphyrin core, and the axial azulenic moieties.