Photocatalytic Oxidation of Bromide to Bromine

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• 作者：Kelvin Yun-Da Tsai ; I-Jy Chang
• 刊名：Inorganic Chemistry
• 出版年：2017
• 出版时间：January 17, 2017
• 年：2017
• 卷：56
• 期：2
• 页码：693-696
• 全文大小：304K
• ISSN：1520-510X

文摘

Three consecutive bimolecular reactions are employed to photocatalyze bromide oxidation to bromine. The system consists of a ruthenium(II) complex, [Ru(deeb)₂(dmbpy)]²⁺ (deeb = 4,4′-diethylester-2,2′-bipyridine; dmbpy = 4,4′-dimethyl-2,2′-bipyridine), 4-bromobenzenediazonium tetrafluoroborate (ArN₂BF₄), and Br^–. Varying reagent concentrations allowed us to optimize the sequence of reactions for product formation. The electronically excited ruthenium complex (*Ru) reacts first with ArN₂BF₄ to produce a ruthenium(III) (Ru^III) intermediate, triggering a subsequent reaction with Br^–. Transient absorption measured at 486 and 380 nm provides insight into the time-dependent concentrations of *Ru, Ru^III, and Br₂^•–. Without interference of back-electron transfer, the rate constant for an equal concentration bimolecular reaction of Br₂^•– was determined to be 5 × 10⁹ M^–1 s^–1. The final products, bromine and tribromide, were spectroscopically characterized, and the turnover number (TON) was 230.