Formation of cobalt-oxygen intermediates by dioxygen activation at a mononuclear nonheme cobalt(ii) center.

ABSTRACT: A mononuclear nonheme cobalt(ii) complex, [(TMG₃tren)Co^II(OTf)](OTf) (1), activates dioxygen in the presence of hydrogen atom donor substrates, such as tetrahydrofuran and cyclohexene, resulting in the generation of a cobalt(ii)-alkylperoxide intermediate (2), which then converts to the previously reported cobalt(iv)-oxo complex, [(TMG₃tren)Co^IV(O)]²⁺-(Sc(OTf)₃)_n (3), in >90% yield upon addition of a redox-inactive metal ion, Sc(OTf)₃. Intermediates 2 and 3 represent the cobalt analogues of the proposed iron(ii)-alkylperoxide precursor that converts to an iron(iv)-oxo intermediate via O-O bond heterolysis in pterin-dependent nonheme iron oxygenases. In reactivity studies, 2 shows an amphoteric reactivity in electrophilic and nucleophilic reactions, whereas 3 is an electrophilic oxidant. To the best of our knowledge, the present study reports the first example showing the generation of cobalt-oxygen intermediates by activating dioxygen at a cobalt(ii) center and the reactivities of the cobalt-oxygen intermediates in oxidation reaction.

SUBMITTER: Malik DD 

PROVIDER: S-EPMC8499697 | biostudies-literature | 2021 Sep

REPOSITORIES: biostudies-literature