A Synthetic Oxygen Atom Transfer Photocycle from a Diruthenium Oxyanion Complex

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• 作者：Amanda R. Corcos ; József S. Pap ; Tzuhsiung Yang ; John F. Berry
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：August 10, 2016
• 年：2016
• 卷：138
• 期：31
• 页码：10032-10040
• 全文大小：599K
• 年卷期：0
• ISSN：1520-5126

文摘

Three new diruthenium oxyanion complexes have been prepared, crystallographically characterized, and screened for their potential to photochemically unmask a reactive Ru—Ru═O intermediate. The most promising candidate, Ru₂(chp)₄ONO₂ (4, chp = 6-chloro-2-hydroxypyridinate), displays a set of signals centered around m/z = 733 amu in its MALDI-TOF mass spectrum, consistent with the formation of the [Ru₂(chp)₄O]⁺ ([6]⁺) ion. These signals shift to 735 amu in 4*, which contains an ¹⁸O-labeled nitrate. EPR spectroscopy and headspace GC-MS analysis indicate that NO₂^• is released upon photolysis of 4, also consistent with the formation of 6. Photolysis of 4 in CH₂Cl₂ at room temperature in the presence of excess PPh₃ yields OPPh₃ in 173% yield; control experiments implicate 6, NO₂^•, and free NO₃^– as the active oxidants. Notably, Ru₂(chp)₄Cl (3) is recovered after photolysis. Since 3 is the direct precursor to 4, the results described herein constitute the first example of a synthetic cycle for oxygen atom transfer that makes use of light to generate a putative metal oxo intermediate.