A cyclometalated osmium(III) complex, [OsIIICl(phpy)(tpy)]+ (OsIII(phpy); phpy = 2-C6H4-2-C5H4N-κC,N) is synthesized from OsIIICl3(tpy) (tpy = 2,26,2″-terpyridine) and 2-phenylpyridine (H-phpy) in the presence of AgPF6, in which the metalated carbon atom is disposed trans to the chlorido ligand. Oxidation of OsIII(phpy) with oxygen atom transfer oxidants such as N-methylmorpholine N-oxide (NMO), N,N-dimethylaniline N-oxide (DMAO), H2O2, t-BuOOH, and m-chloroperoxybenzoic acid (m-CPBA) in CH3CN or electron transfer type oxidants such as (NH4)2S2O8 and ammonium hexanitratocerate (CAN) in H2O/acetone causes oxygen atom insertion between the osmium(III)-carbon bond to give a phenoxido-osmium(III) complex OsIII(O-phpy). Isotope labeling experiments using H218O and kinetic studies as well as calculation studies indicate formation of an organometallic oxido-osmium(V) complex as the active intermediate.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry