Ruthenium Complexes of C,C'-Bis(ethynyl)carboranes: An Investigation of Electronic Interactions Mediated by Spherical Pseudo-aromatic Spacers

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• 作者：Mark A. Fox ; Rachel L. Roberts ; Thomas E. Baines ; Boris Le Guennic ; Jean-Franç ; ois Halet ; Frantisrc="http ; //pubs.acs.org/images/entities/scaron.gif" border="0">ek Hartl ; Dmitri S. Yufit ; Da
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：March 19, 2008
• 年：2008
• 卷：130
• 期：11
• 页码：3566 - 3578
• 全文大小：560K
• 年卷期：v.130,no.11(March 19, 2008)
• ISSN：1520-5126

文摘

The complexes [Ru(1-Cs/entities/tbd1.gif">C-1,10-C₂B₈H₉)(dppe)Cp*] (3a), [Ru(1-Cs/entities/tbd1.gif">C-1,12-C₂B₁₀H₁₁)(dppe)Cp*] (3b), [{Ru(dppe)Cp*}₂{s/entities/mgr.gif">-1,10-(Cs/entities/tbd1.gif">C)₂-1,10-C₂B₈H₈}] (4a) and [{Ru(dppe)Cp*}₂{s/entities/mgr.gif">-1,12-(Cs/entities/tbd1.gif">C)₂-1,12-C₂B₁₀H₁₀}] (4b), which form a representative series of mono- and bimetallic acetylide complexesfeaturing 10- and 12-vertex carboranes embedded within the diethynyl bridging ligand, have been preparedand structurally characterized. In addition, these compounds have been examined spectroscopically (UV-vis-NIR, IR) in all accessible redox states. The significant separation of the two, one-electron anodic wavesobserved in the cyclic voltammograms of the bimetallic complexes 4a and 4b is largely independent of thenature of the electrolyte and is attributed to stabilization of the intermediate redox products [4a]⁺ and [4b]⁺through interactions between the metal centers across a distance of ca. 12.5 Å. The mono-oxidized bimetalliccomplexes [4a]⁺ and [4b]⁺ exhibit spectroscopic properties consistent with a description of these speciesin terms of valence-localized (class II) mixed-valence compounds, including a unique low-energy electronicabsorption band, attributed to an IVCT-type transition that tails into the IR region. DFT calculations withmodel systems [4a-H]⁺ and [4b-H]⁺ featuring simplified ligand sets reproduce the observed spectroscopicdata and localized electronic structures for the mixed-valence cations [4a]⁺ and [4b]⁺.