Palladium(II) complexes with N,N′-bidentate N-methyl-N-(pyridin-2-ylmethyl)aniline and its derivatives: Synthesis, characterization, and methyl methacrylate polymerization

The N,N′-bidentate [(N,N′)PdCl₂] complexes [i.e., [L_nPdCl₂] (L_n = L₁-L₅)] were synthesized by the reaction of [Pd(CH₃CN)₂Cl₂] with N-methyl-N-(pyridin-2-ylmethyl)aniline (L₁) and its derivatives (L₂-L₅) in ethanol. The molecular structures of [L_nPdCl₂] (L_n = L₁-L₃) were characterized using X-ray crystallography, which showed that the Pd atom in the Pd(II) complexes had a square planar geometry involving two nitrogen atoms of N,N′-bidentate and two chlorido ligands. The complexes [L_nPdCl₂] (L_n = L₁-L₅) were investigated for methyl methacrylate (MMA) polymerization in the presence of modified methylaluminoxane (MMAO) at 60°C. Specifically, complex [L₁PdCl₂] showed moderate catalytic activity toward MMA polymerization with an activity of 3.03 × 10⁴ g poly(methylmethacrylate) (PMMA)/mol Pd·h and PMMA syndiotacticity (characterized by ¹H NMR spectroscopy) of ∼0.68.