Unexpected participation of nucleophiles in the reaction of palladium(II) acetate with divalent 3d metals

Transformation of Unsaturated Fatty Acids/Esters to Corresponding Keto Fatty Acids/Esters by Aerobic Oxidation with Pd(II)/Lewis Acid Catalyst

“…In previous studies, through UV–vis, 1 H and 13 C NMR characterizations, it was found that, in acetonitrile, adding nonredox metal ions to Pd­(OAc) 2 leads to the formation of heterobimetallic Pd­(II)/LA species having two acetate bridges. − As a result, binding of Lewis acid to the Pd­(II) species makes it more positively charged as observed by the downshift of the chemical shift of the acetate bridge in 1 H and 13 C NMR spectra, which leads to its improved catalytic efficiency in olefin oxidations. In addition, similar heterobimetallic Pd­(II)/LA salts with acetate bridges were widely reported, including LA = Ba 2+ , Sr 2+ , Ca 2+ , Mn 2+ , Co 2+ , Ni 2+ , Cd 2+ , Nd 2+ , Zn 2+ , and Ce 4+ , and some of those were successfully identified by X-ray single crystal characterizations. − Here, in the identical CH 3 CN/H 2 O solvent, formation of the Pd­(II)/LA species, for example, Pd­(II)/Sc­(III) species, should happen as well as those in previous studies and is responsible for vegetable oil oxidations. It is worth mentioning that a few heterobimetallic Pd­(II)/Cu­(II) complexes were isolated by Hosokawa and Murahashi, and they were active catalysts for olefin oxidations. , …”

Transformation of Methyl Linoleate to its Conjugated Derivatives with Simple Pd(OAc)2/Lewis Acid Catalyst

“…In previous studies, it has been observed by UV-Vis spectra that adding non-redox metal salts like Sc(OTf) 3 or Al(OTf) 3 to Pd(OAc) 2 in acetonitrile would generate the new Pd(II) species, and it was further evidenced by NMR studies [33][34][35]. Taken together with the facts that heterobimetallic Pd(II) dimers having an acetate bridge with bivalent or trivalent metal ions, including Ba 2+ , Sr 2+ , Ca 2+ , Mn 2+ , Co 2+ , Ni 2+ , Cd 2+ , Zn 2+ Ce 3+ , Nd 3+ , Eu 3+ and Ce 4+ , have been widely reported [45][46][47][48], we proposed the formation of the heterobimetallic Pd(II)/Sc(III) or Pd(II)/Al(III) dimer having an acetate bridge as the key species for Wacker-type oxidation, olefin isomerization and oxidative coupling reactions [33][34][35]. In the present studies, the UV-Vis kinetics of Pd(OAc) 2 /Sc(OTf) 3 in toluene/t-BuOH solvent also indicated the formation of the new Pd(II) species.…”

Pd(ii)/LA-catalyzed acetanilide olefination with dioxygen

“…Similar acetate bridged heterometallic Pd(II) cores were even reported in the literature with X-ray characterization. 39,40 Notably, Wu, Yu, and Houk also proposed a similar acetate bridged heterometallic Pd(II)/Ag(I) core as the active species for C-H activation based on DFT calculations, where Ag(I) salts were apparently employed as the oxidant. [41][42][43] Here, adding Sc(OTf ) 3 to the MeCN solution of Pd(OAc) 2 may have converted the dominant monomeric Pd(OAc) 2 with other depolymerized minor {Pd Organic & Biomolecular Chemistry Paper (OAc) 2 } m species to form the unified, diacetate bridged heterobimetallic Pd(II)/Sc(III) core as observed in the single peak of the methyl group at δ H = 1.99 ppm.…”