Active transition metal oxo and hydroxo moieties in nature's redox, enzymes and their synthetic models: Structure and reactivity relationships

Distinct Reactivity Differences of Metal Oxo and Its Corresponding Hydroxo Moieties in Oxidations: Implications from a Manganese(IV) Complex Having Dihydroxide Ligand

“…[6,7] Interestingly, using the method introduced by Bordwell et al and Mayer, [8] it was found that the hydrogen-abstraction ability of a metal oxo moiety and the related metal hydroxo in those models are very similar. [7,9,10] [12] Using Mn IV (salen) complexes (salen = N,N'-bis(salicylidene)ethylenediamine anion), Fujii and co-workers also found that Mn IV = O demonstrates much faster rate than its protonated Mn 2 )] can be investigated under three different pH conditions. Hydrogen abstraction reactions from 9,10-dihydroanthracene substrate were performed in acetone/ water (4:1) under nitrogen, and the product distributions are summarized in Table 1 3+ at pH 1.5 gives a 3.0 % yield of anthracene and an 8.3 % yield of anthraquinone, a surprisingly similar product distribution to that for the Mn IV =O moiety at pH 13.4.…”

“…[6,7] Interestingly, using the method introduced by Bordwell et al and Mayer, [8] it was found that the hydrogen-abstraction ability of a metal oxo moiety and the related metal hydroxo in those models are very similar. [7,9,10] The major difference between the M n+ =O and its corresponding M n+ ÀOH group is their protonation state. The immediate issue is "what are the reactivity relationships between the metal oxo and its corresponding hydroxo intermediate?"…”

Molybdenum Complexes as Catalysts for the Oxidation of Cycloalkanes with Molecular Oxygen

“…Molybdenum complexes are well known as active centers of several enzymes such as oxotransferases [1][2][3][4]. Some molybdates show antiviral, antitumoral or antibiotic activity [5][6][7].…”

Oxidation of Naphthalene with a Manganese(IV) Bis(hydroxo) Complex in the Presence of Acid

“…[7] Only one Mn IV oxo complex led to sluggish oxidation of naphthalene. [11][12][13][14][15][16] In biomimetic studies,afew nonheme high-valent metal hydroxo complexes have been prepared and exhibited CÀHb ond activation reactivity towards aliphatic substrates, [16][17][18][19][20][21][22][23] whereas there are no reports on their reactivity towards aromatic molecules. [9,10] Recently,h igh-valent metal hydroxo intermediates have been suggested as reactive species in lipoxygenase and ligninolytic enzymes.…”

“…[9,10] Recently,h igh-valent metal hydroxo intermediates have been suggested as reactive species in lipoxygenase and ligninolytic enzymes. [11][12][13][14][15][16] In biomimetic studies,afew nonheme high-valent metal hydroxo complexes have been prepared and exhibited CÀHb ond activation reactivity towards aliphatic substrates, [16][17][18][19][20][21][22][23] whereas there are no reports on their reactivity towards aromatic molecules. Herein, we report the very first oxidation reaction of naphthalene with amononuclear Mn IV complex with terminal hydroxide ligands,[ Mn IV (TBDAP)(OH) 2 ] 2+ (2;T BDAP = N,N-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane) in the presence of acid, [24] together with detailed kinetic studies.T o the best of our knowledge,t his is the first report on acidpromoted oxidation with ahigh-valent metal hydroxo species.…”