Selective and efficient oxidation of ethylene to ethylene glycol acetates with H2O2 catalyzed by Pd(OAc)2–di(2-pyridyl)ketone–di(2-pyridyl)methanesulfonate system

Palladium(IV) Monohydrocarbyls: Mechanistic Study of the Ligand-Enabled Oxidation of Palladium(II) Complexes with H2O2 in Water

“…It is reasonable to assume that the corresponding heavier species 25 + – 30 + result from nucleophilic addition of a water molecule across the CO bond of the dpk ligand (Scheme ). Hydration of the carbonyl of di(2-pyridyl)ketone in water is well known and is facilitated by coordination of dpk to the Pd II or Pt II atom. ,, In complexes 1(OAc) and 2(OAc) , derived from 2-benzoylpyridine and having two carbonyl groups, the most electrophilic dpk carbonyl is presumed to be involved in the hydration.…”

“…Both free and metal-coordinated dpk ligand is known to undergo a reversible hydration in water (Scheme ). , Deprotonation of the resulting gem -diol produces a facially chelating 1-hydroxy-di(2-pyridyl)methoxide ligand L that can stabilize the Pd IV center emerging during oxidation reactions.…”

“…Both free and metal-coordinated dpk ligand is known to undergo a reversible hydration in water (Scheme 2). 22,23 Deprotonation of the resulting gem-diol produces a facially chelating 1-hydroxy-di(2-pyridyl)methoxide ligand L that can stabilize the Pd IV center emerging during oxidation reactions. Importantly, in contrast to some other facially chelating ligands that were used to stabilize organopalladium(IV) complexes, such as hydridotris(pyrazolyl)borate, 17 pyridinophanes, 11,20 or 1,4,7-triazacyclononane, 18 the 1-hydroxy-di(2pyridyl)methoxide ligand L contains relatively good leaving groups, the alkoxide and the pyridine fragments, that facilitate reductive elimination of C−OH, C−OAc, C−Cl, and C−Br bonds 8 from the derived Pd IV species.…”

“…Hydration of the carbonyl of di(2-pyridyl)ketone in water is well known and is facilitated by coordination of dpk to the Pd II or Pt II atom. 8,22,23 In complexes 1(OAc) and 2(OAc), derived from 2-benzoylpyridine and having two carbonyl groups, the most electrophilic dpk carbonyl is presumed to be involved in the hydration.…”

Reversible PtII–CH3 deuteration without methane loss: metal–ligand cooperation vs. ligand-assisted PtII-protonation

“…As the search for new metal-ligand platforms for methane functionalization continues, we sought to investigate the κ 2 -(N,N) DPK-supported dimethylplatinum(II) complex, 1 (Scheme 2) from the perspective of exploiting the ability of the keto fragment of DPK to undergo reversible addition of protic molecules leading to potential κ 3 -(N,N,O) coordination modes. Although widely explored in organometallic chemistry, [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] to the best of our knowledge, such involvement has not been investigated in the context of C-H reductive elimination from Pt IV , despite the demonstrated ability of κ 2 -(N,N)-DPKsupported Pt II complexes to activate C-H bonds. [34][35][36] Here, we report that the DPK-supported dimethylplatinum(II) complex (1, Scheme 2), upon dissolution in CD 3 OD, undergoes fast and reversible Pt II -CH 3 deuteration (reductive coupling) at room temperature without methane loss (reductive elimination).…”