Structural and Spectroscopic Characterization of Rhenium Complexes Containing Neutral, Monoanionic, and Dianionic Ligands of 2,2′-Bipyridines and 2,2′:6,2″-Terpyridines: An Experimental and Density Functional Theory (DFT)-Computational Study

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• 作者：Mei Wang ; Thomas Weyhermüller ; Eckhard Bill ; Shengfa Ye ; Karl Wieghardt
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：May 16, 2016
• 年：2016
• 卷：55
• 期：10
• 页码：5019-5036
• 全文大小：881K
• 年卷期：0
• ISSN：1520-510X

文摘

The molecular and electronic structures of the members of the following electron transfer series have been determined by single crystal X-ray crystallography, temperature dependent magnetic susceptibility measurements, and UV–vis–NIR and electron paramagnetic resonance spectroscopy and verified by density functional theory calculations (DFT B3LYP): [Re(^Mebpy)₃]ⁿ, [Re(tpy)₂]ⁿ, [Re(Tp)(bpy)Cl]ⁿ (n = 2+, 1+, 0, 1−), and [Re(bpy)(CO)₃]^1+,0,1– (^Mebpy = 4, 4′-dimethyl-2,2′-bipyridine; Tp^– = tris-pyrazolylborate, tpy = 2, 2′:6, 2″-terpyridine). For each series we show that the average C_py–C_py bond length and the average C–N_chel bond distance vary in a linear fashion with the charge n of the N,N′-coordinated (bpy)ⁿ and N,N′,N″-coordinated (tpy)ⁿ ligand. Consequently, the difference Δ between these two bond lengths varies also linearly with n. Δ is shown to be a useful single marker for the oxidation level of these two heterocyclic ligands (neutral, π-radical anion, and dianion). In addition, we have synthesized and structurally as well as spectroscopically characterized the following complexes: [(^cyDAB^•)Re^IVCl₃(PPh₃)]⁰ 1, [Re^III(tpy^•)Cl(PPh₃)₂]Cl 2, [Re^III(tpy⁰)₂Cl](OTf)₂·2Et₂O 8. There are no structurally significant (experimentally detectable) π-back-bond effects of the neutral bpy⁰ or tpy⁰ ligands irrespective of the d^N configuration (N = 0–7) of the central Re atom.