463301-00-0Relevant academic research and scientific papers
Synthesis of new phosphine imine ligands and their effects on the thermal stability of late-transition-metal olefin polymerization catalysts
Guan, Zhibin,Marshall, William J.
, p. 3580 - 3586 (2002)
A series of α-phosphine imine hybrid ligands was successfully synthesized by nucleophilic substitution of di-tert-butylchlorophosphine or diphenylchlorophosphine on imine anions. These ligands exist as α-phosphine enamines before complexation, which tautomerize to α-phosphine imines upon coordination to Ni(II) or Pd(II). The Ni(II) and Pd(II) complexes with these P∧N ligands were prepared and fully characterized by NMR, elemental analysis, and single-crystal X-ray crystallography. While all the Ni(II)-P∧N complexes assume tetrahedral coordination geometry, the Pd(II)-P∧N complexes are square planar. Upon activation with MAO, the Ni(II) complexes were active for ethylene polymerization. Whereas the Ni(II)-P∧N complexes are less productive than the Brookhart Ni(II)-α-bis(imine) complexes and form polyethylenes with relatively low molecular weight, the thermal stabilities of these complexes upon activation are significantly higher than those of the corresponding Ni(II)-α-bis(imine) complexes. 13C NMR shows that the polyethylenes are highly branched and have branch-on-branches. In contrast, the Pd(II)-P∧N complexes were inactive for ethylene polymerization.
