Rogers Ciarán J, Hardwick Olivia, Corry Thomas A, Rummel Felix, Collison David, Bowen Alice M, O'Malley Patrick J
Department of Chemistry and Photon Science Institute, School of Natural Sciences, The University of Manchester, Manchester M13 9PL, U.K.
ACS Omega. 2022 Nov 3;7(45):41783-41788. doi: 10.1021/acsomega.2c06151. eCollection 2022 Nov 15.
ELDOR-detected nuclear magnetic resonance (EDNMR) spectral simulations combined with broken-symmetry density functional theory (BS-DFT) calculations are used to obtain and to assign the Mn hyperfine coupling constants (hfcs) for modified forms of the water oxidizing complex in the penultimate S state of the water oxidation cycle. The study shows that an open cubane form of the core MnCaO cluster explains the magnetic properties of the dominant = 3 species in all cases studied experimentally with no need to invoke a closed cubane intermediate possessing a distorted pentacoordinate Mn ion as recently suggested. EDNMR simulations found that both the experimental bandwidth and multinuclear transitions may alter relative EDNMR peak intensities, potentially leading to incorrect assignment of hfcs. The implications of these findings for the water oxidation mechanism are discussed.
结合破缺对称性密度泛函理论（BS-DFT）计算的电子检测核磁共振（EDNMR）光谱模拟，用于获得并指定水氧化循环倒数第二个S态中改良形式的水氧化复合物的锰超精细耦合常数（hfcs）。研究表明，核心MnCaO簇的开放立方烷形式解释了所有实验研究案例中占主导地位的S = 3物种的磁性，无需像最近所建议的那样引入具有扭曲五配位锰离子的封闭立方烷中间体。EDNMR模拟发现，实验带宽和多核跃迁都可能改变相对EDNMR峰强度，这可能导致hfcs的错误指定。讨论了这些发现对水氧化机制的影响。
