851474-52-7Relevant articles and documents
Kinetic and mechanistic study of the Pt(II) versus Pt(IV) effect in the platinum-mediated nitrile-hydroxylamine coupling
Luzyanin, Konstantin V.,Kukushkin, Vadim Yu.,Ryabov, Alexander D.,Haukka, Matii,Pombeiro, Armando J. L.
, p. 2944 - 2953 (2008/10/09)
The metal-mediated coupling between coordinated EtCN in the platinum(II) and platinum(IV) complexes cis- and trans-[PtCl2(EtCN)2], trans-[PtCl4(EtCN)2], a mixture of cis/trans-[PtCl 4(EtCN)2] or [Ph3PCH2Ph][PtCl n(EtCN)] (n = 3, 5), and dialkyl- and dibenzylhydroxylamines R 2NOH (R = Me, Et, CH2Ph, CH2C6H 4Cl-P) proceeds smoothly in CH2Cl2 at 20-25°C and the subsequent workup allowed the isolation of new imino species [PtCln{NH=C(Et)-ONR2}2] (n = 2, R = Me, cis-1 and trans-1; Et, cis-2 and trans-2; CH2Ph, cis-3 and trans-3; CH 2C6H4Cl-p, cis-4 and trans-4; n = 4, R = Me, trans-9; Et, trans-10; CH2Ph, trans-11; CH2C 6H4Cl-P, trans-12) or [Ph3PCH 2Ph]-[PtCln{NH=C(Et)ONR2}] (n = 3, R = Me, 5; Et, 6; CH2Ph, 7; CH2C6H4Cl-P, 8; n = 5, R = Me, 13; Et, 14; CH2Ph, 15; CH2C6H 4Cl-p, 16) in excellent to good (95-80%) isolated yields. The reduction of the Pt(IV) complexes 9-16 with the ylide Ph3P=CHCO 2Me allows the synthesis of Pt(II) species 1-8. The compounds 1-16 were characterized by elemental analyses (C, H, N), FAB-MS, IR, 1H, 13C(1H), and 31P{1H} NMR (the latter for the anionic type complexes 5-8 and 13-16) and by X-ray crystallography for the Pt(II) (cis-1, cis-2, and trans-4) and R(IV) (15) species. Kinetic studies of addition of R2NOH (R = CH2C6H4Cl-p) to complexes [Ph3PCH2Ph]-[PtIICl 3(EtCN)] and [Ph3PCH2Ph][PtIVCl 5(EtCN)] by the 1H NMR technique revealed that both reactions are first order in (p-ClC6H4CH2) 2NOH and Pt(II) or Pt(IV) complex, the second-order rate constant k2 being three orders of magnitude larger for the Pt(IV) complex. The reactions are intermolecular in nature as proved by the independence of k 2 on the concentrations of added EtC≡N and Cl-. These data and the calculated values of ΔH? and ΔS? are consistent with the mechanism involving the rate-limiting nucleophilic attack of the oxygen of (p-ClC6H 4CH2)2NOH at the sp-carbon of the C≡N bond followed by a fast proton migration.