Metal ion-coupled electron-transfer reactions of metal-oxygen complexes

Modulation of a μ-1,2-Peroxo Dicopper(II) Intermediate by Strong Interaction with Alkali Metal Ions

“…Reactive intermediates formed upon metal-mediated activation of dioxygen, including superoxo, peroxo, or high-valent metal-oxo species, play key roles in many chemical and biochemical oxidative transformations . It is now increasingly realized that the reactivity of these important intermediates can be modulated by interaction with additional redox-inactive metal ions that serve as Lewis acids. , Often cited as a prominent example from biology is the Ca 2+ ion, which is an integral component of nature’s oxygen-evolving complex (OEC) in photosystem II as part of a Mn 4 CaO 5 core structure . In molecular systems, strongly Lewis acidic metal ions such as Zn 2+ or Sc 3+ have been used to, inter alia , stabilize unusual oxocobalt­(IV) complexes, induce valence tautomerism in high-valent oxomanganese porphyrinoids for enhancing their reactivity, or tune the redox reactivity of oxometal intermediates by enabling metal ion-coupled electron transfer (MCET) .…”

A bioinspired oxoiron(iv) motif supported on a N2S2 macrocyclic ligand

“…For over 40 years, small-molecule complexes synthesized as active-site models of the high-valent intermediates in heme and non-heme oxygenases have advanced our understanding of the catalytic cycles. 3,[11][12][13][14][15][16][17][18][19][20] Despite these efforts, the synthesis of an oxoiron(IV) porphyrin complex with a thiolate ligand has not yet been achieved. Furthermore, [(TMCS)Fe IV (O)] + (TMCS = 1-mercaptoethyl-4,8,11-trimethyl-1,4,8,11-tetraazacyclotetra-decane; (Scheme 1)), represents the only synthetic complex 21 thus far to model the RS-Fe IV QO unit associated with the active oxidants of cytochrome P450 2,6 and chloroperoxidase.…”

Are Free Radicals the Primary Reactive Species in Co(II)-Mediated Activation of Peroxymonosulfate? New Evidence for the Role of the Co(II)–Peroxymonosulfate Complex

“…For example, at pH > 2.0, more than 99% of Co­(III) is calculated to exist in the dimeric form on the basis of the K 1 value. These Co­(III) dimers could further react with free Co­(III) ions to form binuclear Co­(II)–peroxide species ([Co­(II)­OH] 2 5+ ), which is probably responsible for the oxidation of MPSO and formation of MPSO 2 via the oxygen-atom-transfer pathway, likely following similar mechanisms as metal–oxygen species. − In addition, results in Figure S14 in the Supporting Information show that MPSO 2 is not further oxidized at pH = 3.0 and 6.0 in the Co­(III) system. Based on these different oxidation performances of MPSO and MPSO 2 in Co­(III) and Co­(II)/PMS systems, we speculate that Co­(III) is not the major reactive species for the conversion of MPSO in the Co­(II)/PMS system.…”