| Abstract
| - The pincer group [C6H3(CH2NMe2)2-2,6]- (NCN) facilitates the study of reactions at palladium(II), platinum(II), and platinum(IV) centers that model possible steps in the reaction of arenes with acetic acid to form aryl acetates in the presence of oxidizing agents and Pd(II) catalysts. The complexes PtIIX(NCN) react with dibenzoyl peroxide to form PtIV(O2CPh)3(NCN) (X = O2CPh) and PtIV(O2CPh)2Tol(NCN) (X = 4-tolyl), and MII(O2CPh)(NCN) react with iodomethane to form MIII(NCN) (M = Pd, Pt) and Me-O2CPh, where carbon−oxygen bond formation is demonstrated to occur via MIV(O2CPh)2Me(NCN) for platinum.
- The presence of the [2,6-(dimethylaminomethyl)phenyl-N,C,N]- (pincer) ligand (NCN) inplatinum(II) complexes has been used to generate stable organoplatinum(IV) complexes thatmodel possible intermediates and reactivity in metal-catalyzed C−O bond formationprocesses. The complexes M(O2CPh)(NCN) [M = Pd (1), Pt (2)] were obtained by metathesisreactions from the chloro analogues, and although 1 does not react with dibenzoyl peroxide,2 does so to form Pt(O2CPh)3(NCN) (3) as a model intermediate for the acetoxylation ofarenes by acetic acid in the presence of palladium(II) acetate and an oxidizing agent. Thecomplex Pt(O2CPh)(NCN) (2) reacts with iodomethane in a complex manner to form PtI(NCN) (6) and cis-Pt(O2CPh)2Me(NCN) (7). Complex 7 decomposes to form Pt(O2CPh)(NCN)(2) and MeO2CPh, probably via benzoate dissociation followed by nucleophilic attack by thebenzoate ion at the PtIV-Me carbon atom. The Pd(II) analogue Pd(O2CPh)(NCN) (1) reactswith MeI to give PdI(NCN) (8) and MeO2CPh, for which the potential intermediacy of Pd(IV) species could not confirmed by 1H NMR spectroscopy. The complex PtTol(NCN) (4) (Tol= 4-tolyl) reacts with (PhCO2)2 to form cis-Pt(O2CPh)2Tol(NCN) (5), but, unlike the PtIVMeanalogue 7, the PtIVTol complex 5 does not undergo facile C−O bond formation. X-raystructural studies of the isostructural square-planar complexes M(O2CPh)(NCN) (1, 2) andof the octahedral Pt(IV) complexes as solvates 3·1/2Me2CO, 5·Me2CO, and 7·Me2CO·H2Oare reported. Complexes 5 and 7 have cis-PtC2 and cis-Pt(O2CPh)2 configurations.
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