title: Oxygenation by ruthenium monosubstituted polyoxotungstates in aqueous solution: experimental and computational dissection of a Ru(III)-Ru(V) catalytic cycle.
abstract: Molecular polyoxometalates with one embedded ruthenium center, with general formula [Ru(II/III)(DMSO)XW11O39](n-) (X = P, Si; n = 4-6), are readily synthesized in gram scale under microwave irradiation by a flash hydrothermal protocol. These nanodimensional and polyanionic complexes enable aerobic oxygenation in water. Catalytic oxygen transfer to dimethylsulfoxide (DMSO) yielding the corresponding sulfone (DMSO2 ) has been investigated with a combined kinetic, spectroscopic and computational approach addressing: (i ) the Ru(III) catalyst resting state; (ii ) the bimolecular event dictating its transformation in the rate-determining step; (iii ) its aerobic evolution to a high-valent ruthenium oxene species; (iv ) the terminal fate to diamagnetic dimers. This pathway is reminiscent of natural heme systems and of bioinspired artificial porphyrins. The in silico characterization of a key bis-Ru(IV)-μ-peroxo-POM dimeric intermediate has been accessed by density functional theory. This observation indicates a new landmark for tracing POM-based manifolds for multiredox oxygen reduction/activation, where metal-centered oxygenated species play a pivotal role.
authors.affiliation: ITM-CNR and Department of Chemical Sciences, University of Padova Via F. Marzolo, 1, 35131 Padova (Italy).
authors.forename: Andrea
authors.initials: A
authors.lastname: Sartorel
authors.forename: Pere
authors.initials: P
authors.lastname: Miró
authors.forename: Mauro
authors.initials: M
authors.lastname: Carraro
authors.forename: Serena
authors.initials: S
authors.lastname: Berardi
authors.forename: Olga
authors.initials: O
authors.lastname: Bortolini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bagno
authors.forename: Carles
authors.initials: C
authors.lastname: Bo
authors.forename: Marcella
authors.initials: M
authors.lastname: Bonchio
keywords: catalysis; density functional theory; oxygen activation; polyoxometalate