Water Oxidation Catalyzed by a Bioinspired Tetranuclear Manganese Complex: Mechanistic Study and Prediction. Issue 15 (22nd June 2022)

• Record Type: Journal Article
• Authors: Li, Man; Liao, Rong‐Zhen
• Is Part Of: ChemSusChem. Volume 15:Issue 15(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-06-22
• Subjects: density functional calculations -- electrocatalysis -- manganese -- reaction mechanism -- water oxidation; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.202200187
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: Density functional theory calculations were utilized to elucidate the water oxidation mechanism catalyzed by polyanionic tetramanganese complex a [Mn III 3 Mn IV O3 (CH3 COO)3 (A‐α‐SiW9 O34 )] 6− . Theoretical results indicated that catalytic active species 1 (Mn4 III, III, IV, IV ) was formed after O2 formation in the first turnover. From 1, three sequential proton‐coupled electron transfer (PCET) oxidations led to the Mn IV ‐oxyl radical 4 (Mn4 IV, IV, IV, IV −O⋅). Importantly, 4 had an unusual butterfly‐shaped Mn2 O2 core for the two substrate‐coordinated Mn sites, which facilitated O−O bond formation via direct coupling of the oxyl radical and the adjacent Mn IV ‐coordinated hydroxide to produce the hydroperoxide intermediate Int1 (Mn4 III, IV, IV, IV −OOH). This step had an overall energy barrier of 24.9 kcal mol −1 . Subsequent PCET oxidation of Int1 to Int2 (Mn4 III, IV, IV, IV −O2 ⋅) enabled the O2 release in a facile process. Furthermore, apart from the Si‐centered complex, computational study suggested that tetramanganese polyoxometalates with Ge, P, and S could also catalyze the water oxidation process, where those bearing P and S likely present higher activities. Abstract : Float like a butterfly : Density functional theory calculations are employed to investigate the water oxidation mechanism catalyzed by polyanionic tetramanganese complex a ([Mn III 3 Mn IV O3 (CH3 COO)3 (A‐α‐SiW9 O34 )] 6− ). Theoretical results suggest the O−O bond formation occurs at Mn IV ‐oxyl radical (Mn4 IV, IV, IV, IV −Ȯ), which possesses an unusual butterfly‐shaped Mn2 O2 core, via direct coupling of the oxyl radical and the adjacent Mn IV ‐coordinated hydroxide. Prediction of catalytic activity for analogous catalysts is conducted computationally.