Coordination Chemistry of Inversely Polarized Phosphaalkenes toward Group 10 Metal Centers

A series of palladium and platinum complexes containing inversely polarized phosphaalkenes (Me2N)(R)CPR‘ (R = H, R‘ = Mes*, 2; R = Me, R‘ = Mes*, 3; R = H, R‘ = Mes, 4),
exhibiting different steric and electronic environments, have been synthesized. Ligand 2
coordinates in η1-P fashion to either palladium (PdCl2(η1-P)2, 5) or platinum (cis-Pt(Cl)2(η1-P)2, 6; trans-Pt(Cl)2(η1-P)2, 7). The equimolar reaction of 3 with Pd(COD)Cl2 afforded a
mixture in 3/1 ratio of cyclopalladated dimeric complexes [PdCl(κ2-P,C−CH2N(Me)CHPMes*)]2, 9 (cis isomer) and 9‘ (trans isomer). The latter was characterized by X-ray
diffraction. The less hindered ligand 4 acts as bridging phosphido-like ligand with both
palladium (μ-P-[PdCl2(MesPCH(NMe2))]2, 11) and platinium (μ-P-[PtCl2(MesPCH(NMe2))]2,
12). In the platinum case, the reaction of two or more equivalents of the ligand 4 gave a
mixture of the complex containing 2 ligands/Pt and the cationic complex with 3 ligands/Pt,
13. This complex was isolated from the reaction of 3.5 equiv of 4 with the Pt precursor.