New complexes and materials for O2-based oxidations

Key experiments in three developing dioxygen activation and oxo transfer projects are described. First, the Pt–oxo complex, K7Na9PtIV(O)(OH2)(PW9O34)2 (KNa1) is further addressed and its first reactivity is noted (oxo transfer under Ar at ambient temperature to PPh3 forming OPPh3 with nearly quantitative selectivity). Second, an unusually reactive catalyst for aerobic oxygenation of sulfides to sulfoxides (TBANO3 in the presence of TBA4Fe(H2O)PW11O39 in acetonitrile solvent) is reported and its stoichiometry is established to be the desired atom-efficient dioxygenase one (RSR + (1/2)O2 → RS(O)R). Third, a crystalline microporous solid (metal organic framework material) capable of catalyzing air-based oxidations is described. Reaction of the bis(triesterified)hexavanadate unit terminating in two carboxylate functions, [(n-C4H9)4N]2[V6O13{(CH2O)3CNHCH2(4-C6H4COOH)}2] reacts with Co(NO3)2·6H2O and 4,4′-bipyridine to form a ladder-like microporous polymer, characterized by X-ray crystallography, that catalyzes the air-based oxidation of a representative thiol, n-PrSH, cleanly to the corresponding disulfide, PrSSPr. The esterified hexavanadate units are the catalysts, and there is no reaction in the absence of the microporous material.

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