Distinctive Aspects in Aquation, Proton-Coupled Redox, and Photoisomerization Reactions between Geometric Isomers of Mononuclear Ruthenium Complexes with a Large-π-Conjugated Tetradentate Ligand
Distinctive Aspects in Aquation, Proton-Coupled Redox, and Photoisomerization Reactions between Geometric Isomers of Mononuclear Ruthenium Complexes with a Large-π-Conjugated Tetradentate Ligand
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单核钌配合物与大π-共轭四齿配体的几何异构体之间的水合、质子耦合氧化还原和光异构化反应的独特之处
DOI：
10.1021/acs.inorgchem.2c01937
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发表时间：
2022
影响因子：
4.6
通讯作者：
Yagi Masayuki
中科院分区：
文献类型：
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作者：
Tsubonouchi Yuta;Watanabe Takeumi;Yoshida Kazuha;Watabe Shunsuke;Inaba Keisuke;Hirahara Masanari;Hatanaka Tsubasa;Funahashi Yasuhiro;Chandra Debraj;Hoshino Norihisa;Zahran Zaki N.;Yagi Masayuki
新合成了单核钌(II)配合物的几何异构体，远端/近端-[Ru(tpy)(dpda)Cl]+(d-/p-RuCl, tpy = 2,2′:6′,2″-三联吡啶, dpda = 2,7-双(2-吡啶基)-1,8-二氮杂蒽) 全面研究异构体之间各种反应的几何和电子结构以及独特方面。 d-/p-RuClisomers 的紫外 (UV)-可见光吸收光谱分别在 576 和 573 nm 的近波长处显示出金属配体电荷转移 (MLCT) 的强谱带。然而，时间依赖性密度泛函理论（TD-DFT）计算表明，d-RuC 的 MLCT 跃迁主要涉及到 dpda 配体 π* 轨道的单跃迁，而 p-RuCl 的 dpda 和 tpy 配体的 π* 轨道混合。 p-RuCl 的水化反应 (1.5 × 10–3s–1) 生成近端-[Ru(tpy)(dpda)(OH2)]2+(p-RuH2O) 比 d-RuClin D2O/CD3OD (4:1 v/v) 的水化反应 (5.3 × 10–6s–1) 快三个数量级，这是由较长的 Ru–Cl 键导致的 0.017埃 以及由于 Cl 和 p-RuCl 的 dpda 之间的空间排斥而导致 Cl-Ru-N（dpda 的氮，位于 tpy 平面上）的扭曲角（100.2（3）°）。电化学测量表明，d-RuH2O 在 pH 1-9 时经历了 1H+ 耦合 1e-过程的 2 步氧化反应，RuII-OH2/RuIII-OH 和 RuIII-OH/RuIV=O，而 p-RuH2O 经历了 2H+ 耦合 2e-过程的 1 步氧化反应。 RuII–OH2/RuIV=O，pH 范围为 1–10。在水溶液中观察到 d-RuH2Otop-RuH2O 的不可逆光致异构化，在 520 nm 处内量子产率 (Φ) 为 5.4 × 10–3%，与具有类似二齿配体而不是 dpda 的单核 Ru(II) 水合物的 Φ = 1.1–2.1% 相比，低三个数量级。这可能归因于根据能隙定律，由于 dpda 配体的 π* 能级较低，从激发 3MLCT 态到基态 Ford-RuH2O 的非辐射衰减速率更快：该速率随着能隙的增加呈指数下降。
Geometric isomers of mononuclear ruthenium(II) complexes,distal-/proximal-[Ru(tpy)(dpda)Cl]+(d-/p-RuCl, tpy = 2,2′:6′,2″-terpyridine, dpda = 2,7-bis(2-pyridyl)-1,8-diazaanthracene), were newly synthesized to comprehensively investigate the geometric and electronic structures and distinctive aspects in various reactions between isomers. The ultraviolet (UV)–visible absorption spectra ofd-/p-RuClisomers show intense bands for metal-to-ligand charge transfer (MLCT) at close wavelengths of 576 and 573 nm, respectively. However, time-dependent density functional theory (TD-DFT) calculations suggest that the MLCT transition ofd-RuClinvolves mainly single transitions to the π* orbital of the dpda ligand in contrast to mixing of the π* orbitals of the dpda and tpy ligands forp-RuCl. The aquation reaction (1.5 × 10–3s–1) ofp-RuClto yieldproximal-[Ru(tpy)(dpda)(OH2)]2+(p-RuH2O) is faster than that (5.3 × 10–6s–1) ofd-RuClin D2O/CD3OD (4:1 v/v) by three orders of magnitude, which resulted from the longer Ru–Cl bond by 0.017 Å and the distorted angle (100.2(3)°) of Cl–Ru–N (a nitrogen of dpda, being on a tpy plane) due to the steric repulsion between Cl and dpda forp-RuCl. Electrochemical measurements showed thatd-RuH2Oundergoes a 2-step oxidation reaction of 1H+-coupled 1e–processes of RuII–OH2/RuIII–OH and RuIII–OH/RuIV═O at pH 1–9, whereasp-RuH2Oundergoes a 1-step oxidation reaction of a 2H+-coupled 2e–process of RuII–OH2/RuIV═O in the pH range of pH 1–10. The irreversible photoisomerization fromd-RuH2Otop-RuH2Owas observed in aqueous solution with an internal quantum yield (Φ) of 5.4 × 10–3% at 520 nm, which is lower compared with Φ = 1.1–2.1% of mononuclear Ru(II) aquo complexes with similar bidentate ligands instead of dpda by three orders of magnitude. This is possibly ascribed to the faster nonradiative decay rate from the excited3MLCT state to the ground state ford-RuH2Odue to the lower π* level of dpda ligands according to the energy-gap law: the rate decreases exponentially with the increasing energy gap.