Structure and Reactivity of Nonporphyrinic Terminal Manganese(IV)-Hydroxide Complexes in the Oxidative Electrophilic Reaction.

High-valent transition metal-hydroxide complexes have been proposed as essential intermediates in biological and synthetic catalytic reactions. In this work, we report the single-crystal X-ray structure and spectroscopic characteristics of a mononuclear nonporphyrinic Mn-(OH) complex, [Mn(Me-TPADP)(OH)(OCHCH)] (), using various physicochemical methods. Likewise, [Mn(Me-TPADP)(OH)(OCHCF)] (), which is thermally stable at room temperature, was also synthesized and characterized spectroscopically. The Mn-(OH) adducts are capable of performing oxidation reactions with external organic substrates such as C-H bond activation, sulfoxidation, and epoxidation. Kinetic studies, involving the Hammett correlation and kinetic isotope effect, and product analyses indicate that and exhibit electrophilic oxidative reactivity toward hydrocarbons. Density functional theory calculations support the assigned electronic structure and show that direct C-H bond activation of the Mn-(OH) species is indeed possible.