Neutral Imino-Methyl Benzenesulfonate-Ligated Pd(II) Complexes and Implications in Ethylene Polymerization.

A reaction between sodium 2-formylbenzenesulfonate and aniline revealed the near-quantitative (91%) formation of sodium-2-((phenylimino)methyl)benzenesulfonate . The identity of was unambiguously ascertained using spectroscopic and analytical methods. The scope of this methodology was widened and various electron-donating amines were treated with sodium 2-formylbenzenesulfonate, and a small library of 6 imine ligands was generated. When was treated with [(COD)PdMeCl], instead of the anticipated [PdMe(DMSO)] complex, the formation of [(DMSO)PdClMe] was observed. Nevertheless, the desired imino-methyl benzenesulfonate-ligated palladium complex [PdMe(Lu)] was obtained by in situ abstraction of chloride and addition of bulky 2,6-lutidine as the donor group. The observation of characteristic Pd-Me protons at 0.06 ppm and the corresponding carbon at -8.1 ppm indicated the formation of . These 1D NMR observations were corroborated by 2D C-H correlation spectra and mass analysis, and the existence of was unambiguously ascertained. Along the same lines, and were treated with a palladium precursor to produce [PdMe(Lu)]-type complexes in 55-84% yield, and their identity was established by using a combination of spectroscopic tools, analytical methods, and single-crystal X-ray diffraction. The synthetic utility of has been demonstrated by utilizing these complexes in the insertion polymerization of ethylene to polyethylene.