Cyclometallated platinum(II) compounds with imine ligands derived from amino acids: Synthesis and oxidative addition reactions

The reactions of PtMe₂(μ-SMe₂)]₂ with imines 4-ClC₆H₄CHNCHRCO₂Me (R = H (1a), Me (1b), ⁱPr (1c), CH₂C₆H₄(4’-OH) (1d), C₆H₅ (1e), CH₂C₆H₅(1f)) derived from natural amino acids produced under mild conditions cyclometallated platinum(II) compounds PtMe{κ²-(C,N)-4-ClC₆H₃CHNCHRCO₂Me}(SMe₂)] (2a-2f). These compounds gave the corresponding phosphine derivatives PtMe{κ²-(C,N)-4-ClC₆H₃CHNCHRCO₂Me}(PPh₃)] (3a-3f). The corresponding cyclometallated platinum(IV) compounds PtMe₂I{κ²-(C,N)-4-ClC₆H₃CHNCHRCO₂Me}(PPh₃)] (4) arising from intermolecular oxidative addition of methyl iodide were obtained with a high degree of stereo selectivity. Analogous results were obtained for imine 2,6-Cl₂C₆H₃CHNCH(CH₂C₆H₅)CO₂Me (1g) in a process involving intramolecular oxidative addition of a C-Cl bond. The obtained compounds were fully characterized including structure determinations for compounds 3f, 4d and 4f.