Redox and spectral properties of the four-electron oxidant trans-aquadioxo(terpyridine)ruthenium(2+) diperchlorate

Kinetic study of 2-propanol and benzyl alcohol oxidation by alkaline hexacyanoferrate(III) catalyzed by a terpyridyl ruthenium complex

“…A rapid two-electron oxidation of the resulting Ru II complex would afford a (TrpyO)Ru IV (L)(LЈ)(LЉ) complex where (TrpyO) Ϫ is the hydroxylated (and deprotonated) terpyridine ligand and L, LЈ, LЉ are oxo, hydroxyl, aquo, and/ or chloro ligands. The oxidation chemistry of (Bpy) 2 Ru II (OH 2 ) 2 2ϩ and (Trpy)Ru II (OH 2 ) 3 3ϩ suggests that the high oxidation state of the catalytic species will likely encourage one or more of its ligands to be oxo groups [16,17]. Since reported dimeric and trimeric polypyridine ruthenium complexes all exhibit strong absorption peaks at 600 nm and longer [18], the 472 nm absorption of the catalytic species seems characteristic of a monomer.…”

“…Terpyridine ruthenium-oxo/hydroxyl complexes are noted to have multiple protonation states [16,17], and protonation would enhance the electrophilicity and reactivity of the ruthenium center. Interestingly, proton transfer to and from ruthenium-oxo/hydroxyl complexes can be relatively slow due to accompanying isomerization of the complex.…”

“…The partial charge that accumulates on the alcohol carbon would depend on the relative timing of these two events; electron-withdrawing substituents would encourage more alcohol deprotonation and more nega- Since the hydroxide dependence in the kinetics precludes attack of solution hydroxide in k 2 or k 3 , the catalyst may be responsible for both C 9 H and O 9 H cleavage as part of a pericyclic process (Scheme I). Overall, this would amount to a two-electron -two-proton reduction of the catalyst, which is not surprising in light of the familiar proton-coupled electrochemistry of ruthenium-aquo/ hydroxyl/oxo complexes [16,17]. Although pericyclic mechanisms have been proposed for the oxidation of coordinated alcohols in chromium(VI)-, rhenium(V)-, and ruthenium(VI)-oxo complexes, this system provides evidence for a possible pericyclic oxidation of an uncoordinated alcohol [27 -33].…”

Enhanced electrochemical and electrocatalytic activity of a new supramolecular manganese-porphyrin species containing four bis(bipyridine)(aqua)ruthenium(II) complexes

“…High-valence transition metal-oxo complexes, such as the manganese and iron porphyrins [1][2][3][4][5][6][7], and the oxo-ruthenium polypyridines [8][9][10][11][12][13][14][15][16][17][18], have been studied with great interest as oxygen atom transfer catalysts. The cis-[Ru(bipy) 2 (py)O] 2þ species (bipy, 2,2 0 -bipyridine; py, pyridine), for instance, is known to be an efficient catalyst for oxidation of organic and inorganic substrates, performing also DNA oxidation and cleavage either by activation of the 1 0 -ribose C-H bond or by oxo transfer to the guanine nucleobase [19][20][21][22][23][24][25][26][27].…”

Interfaces e dispositivos baseados em porfirinas supramoleculares

“…A diferença entre os dois mecanismos situa-se não apenas no mecanismo químico, mas na eficiência dos processos. [287][288][289][290][291][292][293] , por exemplo a oxidação e quebra da fita de DNA tanto por ativação da ligação 1´-ribose quanto por transferência de grupo oxo para o resíduo de guanina [294][295][296][297] .…”