Synthesis and Characterization of the κ2-acac-O,O Complex OsIV(acac)2PhCl and Study of CH Activation with Benzene

Autor:	Kenneth J. H. Young, Timothy Stewart, Robert J. Nielsen, Roy A. Periana, Mu Jeng Cheng, Oleg Mironov, William A. Goddard
Rok vydání:	2011
Předmět:	Chemistry Organic Chemistry Intermolecular force Inorganic chemistry Medicinal chemistry Catalysis Inorganic Chemistry chemistry.chemical_compound Oxidation state Yield (chemistry) Atom Physical and Theoretical Chemistry Benzene Trifluoromethanesulfonate Stoichiometry
Zdroj:	Organometallics. 30:5088-5094
ISSN:	1520-6041 0276-7333
DOI:	10.1021/om1010512
Popis:	We have synthesized and fully characterized the air-stable complex (κ^2-acac-O,O)2Os^(IV)(Ph)Cl (Cl-1-Ph; acac-O,O = acetylacetonate), which reacts with C_6D_6 to generate Cl-1-Ph-d_5 in high yield and catalyzes the H/D exchange reaction between benzene and toluene-d_8 upon heating to 140 °C. To our knowledge, this is the first example of stoichiometric and catalytic, homogeneous, intermolecular CH activation of arenes by a discrete Os complex. The reactions show extended induction periods. DFT studies of Cl-1-Ph and cis-(κ^2-acac-O,O)_2Os^(III)(C_6H_5)(C_6D_6) (cis-(C_6D_6)-2-Ph) found a mechanism involving CH activation by traces of Os(III) and Cl atom transfer between Cl-1-Ph and cis-(C_6D_6)-2-Ph. Experimental data showing that addition of reductants eliminates the induction periods suggest that CH activation occurs from an oxidation state lower than Os^(IV), consistent with the DFT predictions. Consistent with a Cl atom transfer mechanism, the triflate analogue of Cl-1-Ph, OTf-1-Ph, does not undergo a stoichiometric or catalytic reaction with C_6D_6.
Databáze:	OpenAIRE
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