Catalytic Shilov Chemistry:  Platinum Chloride-Catalyzed Oxidation of Terminal Methyl Groups by Dioxygen

Hydrocarbon C—H Bond Activation with Tp'Pt Complexes

“…NMR characterization at low temperature of the first Pt(II)^2-benzene adduct was recently reported (59). In our Tp'Pt system, acid induced reductive elimination of benzene from the phenyl dihydride complex 12 afforded a surprisingly stable Pt(II)-r| 2 -benzene adduct [^-(HTpOPtiC^^^CeHôîiH^fBAry (17) which was crystallized and examined by X-ray crystallography (83). These Pt(II) rf-arene adducts were probed with NMR techniques, and for the benzene hydride adduct 17 (83) and the p-xylene adduct 19 (84) single crystal X-ray structural analysis was accomplished.…”

“…Although the Shilov oxidation remains one of the most well known examples of homogeneous C-H activation, this system consumes stoichiometric platinum(IV) as the oxidant, an economically and environmentally unacceptable restriction. Advancements have been made toward replacement of platinum(IV) by less expensive oxidants, such as SO3 (8), 0 2 with copper salts (17), or heteropoly acids (18), however, an economical process that catalyzes methane oxidation to methanol has yet to be reported. The mechanism of the Shilov oxidation has been extensively studied by Bercaw, Labinger, and co-workers in hopes of gaining insight to guide the design of catalysts capable of C-H activation and functionalization (7,15,(19)(20)(21)(22)(23).…”

Recent Advances in the Platinum-mediated CH Bond Functionalization

“…The deuterium isotope effect was found to be 1.41±0.01 and 1.91±0.04 respectively, consistent with the hypothesis that coordination of carboxylate anion to Pt II precedes the CH bond cleavage which is the reaction rate limiting step. Though the catalyst resting state was not reported, it is very likely that different redox couples could be involved for different metals, Pd II /Pd 0 for palladium [15] and both Pt IV /Pt II [1,16] and Pt II /Pt 0 for platinum. The authors suggested a single mechanism of platinum catalyzed oxidation with the Pt II /Pt 0 couple.…”

PtII‐Catalyzed Hydroxylation of Terminal Aliphatic C(sp3)−H Bonds with Molecular Oxygen

“…To ensure a more efficient electron transfer chain between Pt II and O 2 , together with a faster reoxidation of possibly formed Pt 0 , the addition of a redox mediator was originally proposed by Gol′dshlger et al . Even though Cu II , Fe III and certain heteropolyacids, for example, H 5 PV 2 Mo 10 O 40 , have proven to be reasonably efficient in activating O 2 , proper systems that combine a sufficiently active and stable catalyst with high alcohol and terminal selectivity remain elusive.…”