Competition between intramolecular oxidative addition and ortho metalation in organoplatinum(II) compounds: activation of aryl-halogen bonds

Diarylplatinum(II) Compounds as Versatile Metallating Agents in the Synthesis of Cyclometallated Platinum Compounds with N-Donor Ligands

“…These reactions gave, in addition to cyclometallated platinum(II) and platinum(IV) compounds analogous to those described for the dimethylplatinum precursor, a new type of platinum(II) compound with a seven-membered metallacycle when X = Cl (Scheme 7). In agreement with previous results for the chemistry of dimethylplatinum analogues [41][42][43], a concerted mechanism is suggested for intramolecular C-X bond activation [61]; for X = Br a platinum(IV) compound is obtained at room temperature, while for X = H a platinum(II) compound is formed along with reductive elimination of benzene after refluxing in toluene the corresponding coordination compounds. Unexpectedly, under the conditions required for intramolecular activation of the C-Cl bond, a seven-membered metallacycle including a biaryl linkage is formed.…”

“…Thus, for electron-rich platinum precursors such as [PtMe 2 (dmso) 2 ] [31][32][33][34][35][36] or dimer [Pt 2 Me 4 (μ-SMe 2 ) 2 ] [37][38][39][40][41][42][43], the initial coordination of the ligand is followed by a cyclometallation step which, in this case, consists on oxidative addition followed by reductive elimination of methane. As shown in Scheme 1, in addition to formation of cyclometallated platinum(II) compounds, dimethylplatinum precursors allow formation of stable cyclometallated platinum(IV) compounds arising from intramolecular activation of C-X bonds (X = Cl, Br) [41][42][43] of adequately designed ligands. In recent years, several diarylplatinum(II) compounds containing labile ligands such as dimethylsulfoxide or dialkylsulfide have also been tested as metallating agents for N-donor ligands.…”

Bidentate and terdentate (P-N-S) complexes of a new thioether azine phosphine Z,E-PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4) with molybdenum, tungsten, or platinum

“…gen (2,12,43,44) or sulfur (45,46). Protonation of the dimethylplatinum(I1) complex 10 with 1 equivalent of picric acid [HOC6H2(N02)3-2,4,6] gave the methylplatinum(I1) picrate salt 12 and methane.…”

Kinetics and mechanism of oxidative addition of MeI to binuclear cycloplatinated complexes containing biphosphine bridges: Effects of ligands

“…Oxidative addition of carbon-halide or other bonds to monomeric organoplatinum(II) complexes, especially those containing diimine ligands, has been extensively studied [4e10]. The most common mechanism of oxidative addition of alkyl halides is the classical S N 2 mechanism involving a second-order rate law (rate ¼ k 2 [complex] [halide]), although in some relatively rare cases, the reactions proceed by concerted addition via a threeecenter transition state (mostly for aryl halides) [5,11,12] or by radical mechanisms, e.g. as observed for isopropyl iodide [13].…”