Highly Accurate Excited-State Structure of [Os(bpy)2dcbpy]2+ Determined by X-ray Transient Absorption Spectroscopy

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• 作者：Xiaoyi Zhang ; Sophie E. Canton ; Grigory Smolentsev ; Carl-Johan Wallentin ; Yizhu Liu ; Qingyu Kong ; Klaus Attenkofer ; Andrew. B. Stickrath ; Michael W. Mara ; Lin X. Chen ; Kenneth W盲rnmark ; Villy Sundstr枚m
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：June 18, 2014
• 年：2014
• 卷：136
• 期：24
• 页码：8804-8809
• 全文大小：331K
• 年卷期：v.136,no.24(June 18, 2014)
• ISSN：1520-5126

文摘

Determining the electronic and geometric structures of photoexcited transient species with high accuracy is crucial for understanding their fundamental photochemistry and controlling their photoreactivity. We have applied X-ray transient absorption spectroscopy to measure the XANES and EXAFS spectra of a dilute (submillimolar) solution of the osmium(II) polypyridyl complex [Os(bpy)₂dcbpy](PF₆)₂ (dcbpy = 4,4鈥?dicarboxy-2,2鈥?bipyridine) (OsL₂L鈥? in methanol at the Os L_III edge. We have obtained spectra of superb quality for both the ground state and the photoinduced ³MLCT excited state that have allowed us not only to extract detailed information about the Os 5d orbitals but also to resolve very small differences of 0.010 卤 0.008 脜 in the average Os鈥揘 bond lengths of the ground and excited states. Theoretical calculations using a recently developed DFT-based approach support the measured electronic structures and further identify the nature of the molecular orbitals that contribute to the main absorption bands in the XANES spectra.