Redox Reactivity of a Mononuclear Manganese-Oxo Complex Binding Calcium Ion and Other Redox-Inactive Metal Ions

• DOI: 10.1021/jacs.8b11492
• Publication Date: 2018-12-24T07:51:47Z
• Authors: Muniyandi Sankara...; Yong-Min Lee; Yuliana Pineda-Ga...; Deepika G. Karmalkar; Mi Sook Seo; So Hyun Jeon; Yulia Pushkar; Shunichi Fukuzumi; Wonwoo Nam
• Keywords: Reactivity; Moiety

Mononuclear nonheme manganese(IV)-oxo complexes binding calcium ion and other redox-inactive metal ions, [(dpaq)MnIV(O)]+-M n+ (1-Mn+, M = Ca2+, Mg2+, Zn2+, Lu3+, Y3+, Al3+, Sc3+) (dpaq 2-[bis(pyridin-2-ylmethyl)]amino- N-quinolin-8-yl-acetamidate), were synthesized by reacting a hydroxomanganese(III) complex, [(dpaq)MnIII(OH)]+, with iodosylbenzene (PhIO) in the presence of ions (M n+). The Mn(IV)-oxo characterized using various spectroscopic techniques. In reactivity studies, we observed contrasting effects on 1-M redox reactions such as electron-transfer (ET), oxygen atom transfer (OAT), hydrogen (HAT) reactions. OAT ET reactions, order n+, 1-Sc3+ ≈ 1-Al3+ > 1-Y3+ 1-Lu3+ 1-Zn2+ 1-Mg2+ 1-Ca2+, follows Lewis acidity bound to Mn-O moiety; that is, stronger higher becomes. sharp contrast, HAT reaction was reversed, giving 1-Ca2+ 1-Lu3+> 1-Y3+> 1-Sc3+; is lower reaction. latter result implies moiety can modulate basicity metal-oxo moiety, thus influencing n+; cytochrome P450 utilizes axial thiolate ligand increase iron-oxo which enhances compound I C-H bond activation