Oxidative addition chemistry of dimethyl(dipyridyl ketone)platinum(II)

Abstract

The dimethylplatinum(II) complex [PtMe2(DPK)] (DPK = di-2-pyridyl ketone) undergoes easy oxidative addition to give platinum(IV) complexes. For example, reaction of [PtMe2(DPK)] with MeI gave [PtIMe3(DPK)], reaction with N-chlorosuccinimide in methanol gave [PtCl(OMe)Me2(DPK)], and reaction with [FN(CH2CH2)2NCH2Cl][BF4]2 in MeCN gave [PtF(NCMe)Me2(DPK)][BF4]. In several cases, the ketone group of the DPK ligand took part in the reactions. For example, oxidation of [PtMe2(DPK)] by air or hydrogen peroxide gave [Pt(OH)Me2(DPKOH)] (DPKOH = κ3-NN′O-(2-C5H4N)2C(OH)O), which reacted with HCl to give [PtClMe2(DPKOH)] or with excess acetyl chloride to give [PtCl2Me2(DPK)]. Reaction of [PtMe2(DPK)] with methyl triflate in MeCN solution gave [PtMe3(NCMe)(DPK)][OTf], which reacted with more MeOTf in the presence of base to give [PtMe3{DPC(OMe)2}][OTf], where DPC(OMe)2 = κ3-NN′O-(2-C5H4N)2C(OMe)2. Hydrolysis of [PtF(NCMe)Me2(DPK)][BF4] gave [Pt{NHC(=O)Me}Me2(DPKOH)], which crystallized in partially protonated form as an unusual supramolecular polymer [Pt{NHC(=O)Me}Me2(DPKOH)]·0.5HBF4.Key words: platinum, oxidative addition, ketone, pyridyl.

Reactions of Five-Coordinate Platinum(IV) Complexes with Molecular Oxygen

“…The alkoxide complex 6 was characterized by NMR spectroscopy and X-ray crystallography, confirming both the coordination of oxygen to the metal and the formal insertion of an oxygen atom into the C–H bond of the central carbon of the ligand backbone. Complex 6 is structurally similar to Pt hemiketal ring systems prepared by Puddephatt and co-workers . In the room-temperature 1 H NMR spectrum of 6 in toluene- d 8 , resonances for the axial Pt–Me group (0.72 ppm, 2 J Pt–H = 72 Hz) and the equatorial Pt–Me groups (1.21 ppm, 2 J Pt–H = 70 Hz) could be identified but were somewhat broadened, while the resonances of the ligand were sharp.…”

“…Complex 6 is structurally similar to Pt hemiketal ring systems prepared by Puddephatt and co-workers. 11 In the roomtemperature 1 H NMR spectrum of 6 in toluene-d 8 , resonances for the axial Pt−Me group (0.72 ppm, 2 J Pt−H = 72 Hz) and the equatorial Pt−Me groups (1.21 ppm, 2 J Pt−H = 70 Hz) could be identified but were somewhat broadened, while the resonances of the ligand were sharp. The Pt−Me resonances sharpened at lower temperatures and broadened into the baseline at 50 °C, suggesting fluxionality similar to that observed for 5.…”

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

“…This is not surprising, especially for Pd II complexes with one hydrocarbyl ligand, assuming the anticipated high reactivity of their Pd IV derivatives. Very few Pd IV monohydrocarbyls have been reported to date. ,, To improve the chances of detecting and isolating high-valent palladium species produced in reactions of organopalladium(II) complexes with O 2 and H 2 O 2 , we use facially chelating tridentate ligands that have been shown theoretically , and experimentally to stabilize octahedral d 6 metal complexes and, specifically, Pd IV compounds. − Previously we reported the use of the di(2-pyridyl)ketone (dpk) ligand for the generation of Pd IV monohydrocarbyls 3(OAc) , 4(OAc) , and 8(OAc) by oxidation with H 2 O 2 of the respective Pd II precursors 1(OAc) , 2(OAc) ,and 7(OAc) (Scheme ) . These Pd IV complexes were characterized in detail and were shown to form products of C–O bond reductive elimination, corresponding phenols 5 or 6 , or Pd II phenoxide 9(OAc) , in high yield at 20–50 °C.…”

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

“…The dpk ligand, a derived semiketal or gem-diol can act as bidentate ligands with respect to a d 8 metal center. In the form of a singly deprotonated semiketal or gem-diol, the dpk can act as a tridentate fac-chelating ligand [23,30e32], stabilize a d 6 metal center, such as in Pd IV [23] and Pt IV [32] complexes, and enable facile oxidation of Pd II monohydrocarbyls to Pd IV monohydrocarbyls with H 2 O 2 in aqueous solutions [23].…”