Mechanism of electrophilic cleavage of the PtC bond in trans-[PtX(CH2CMe3)(PEt3)2] by HX (X=Cl, Br)

Mechanistic Aspects of C−H Activation by Pt Complexes

“…Several studies have served to provide a detailed understanding of the mechanism of protonation of (PEt 3 ) 2 Pt(Me)Cl and closely related systems. Protonations have been proposed to occur directly at the metal, by electrophilic attack at the Pt−C bond, or by a concerted (σ-bond metathesis) pathway; ,− interestingly, the current view (Scheme ) is in essence a slightly modified form of the initial mechanism proposed by Belluco et al The Pt(IV) phosphine complex (PEt 3 ) 2 PtCl 2 (Me)(H) was obtained from (PEt 3 ) 2 Pt(Me)Cl and HCl at −78 °C and eliminated methane at −45 °C in CD 2 Cl 2 . Addition of DOTf to (PEt 3 ) 2 Pt(Me)Cl in CD 3 OD produced no observable hydride, but slow generation of (PEt 3 ) 2 PtCl 2 was accompanied by production of all methane isotopomers in solution; multiple D incorporation into unreacted Pt−methyl was also seen.…”

Oxidative Addition Reactions of Organoplatinum(II) Complexes with Nitrogen-Donor Ligands

“…The cleavage of metal−carbon σ bonds by electrophiles such as protic acids is of fundamental importance in organometallic chemistry, and the mechanism of this process has been the subject of several studies (Scheme ). − Detection of the alkyl(hydrido)platinum(IV) intermediate would provide definitive evidence for an oxidative addition pathway in the protonolysis of Pt−C bonds, although it is difficult to achieve owing to the facile reductive elimination of the alkane. Recently, a few groups have reported the detection and, in some cases, isolation of alkyl(hydrido)platinum(IV) complexes by protonation of the corresponding alkylplatinum(II) complex with HX.…”

On the Mechanism of Palladium-Catalyzed Aromatic C−H Oxidation

“…Conceptually, subsequent oxidative functionalization of the nascent Pd–C bond can proceed by several different mechanisms (Scheme 1). Direct electrophilic Pd–C bond cleavage via intermediate A would proceed without oxidation state change at palladium 8. Alternatively, metal-centered oxidation would afford a high-valent Pd complex, such as dinuclear Pd(III) intermediate B or mononuclear Pd(IV) intermediate C , which would afford the observed products via reductive elimination.…”