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Spectroscopic Capture and Reactivity of a Low‐Spin Cobalt(IV)‐Oxo Complex Stabilized by Binding Redox‐Inactive Metal Ions
Author(s) -
Hong Seungwoo,
Pfaff Florian F.,
Kwon Eunji,
Wang Yong,
Seo MiSook,
Bill Eckhard,
Ray Kallol,
Nam Wonwoo
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201405874
Subject(s) - chemistry , cobalt , redox , reactivity (psychology) , metal , metal ions in aqueous solution , electrophile , inorganic chemistry , photochemistry , organic chemistry , catalysis , medicine , alternative medicine , pathology
High‐valent cobalt‐oxo intermediates are proposed as reactive intermediates in a number of cobalt‐complex‐mediated oxidation reactions. Herein we report the spectroscopic capture of low‐spin ( S =1/2) Co IV ‐oxo species in the presence of redox‐inactive metal ions, such as Sc 3+ , Ce 3+ , Y 3+ , and Zn 2+ , and the investigation of their reactivity in CH bond activation and sulfoxidation reactions. Theoretical calculations predict that the binding of Lewis acidic metal ions to the cobalt‐oxo core increases the electrophilicity of the oxygen atom, resulting in the redox tautomerism of a highly unstable [(TAML)Co III (O . )] 2− species to a more stable [(TAML)Co IV (O)(M n + )] core. The present report supports the proposed role of the redox‐inactive metal ions in facilitating the formation of high‐valent metal–oxo cores as a necessary step for oxygen evolution in chemistry and biology.