Synthesis, structure and catalytic activity of phosphine-substituted zirconium salicylaldiminato complexes

The reaction of the lithium iminophenolate LiOC6H3-2-But-6-CHdouble bond; length as m-dashNAr, where Ar = 3-C6H4P{C6H3(CF3)2-3,5}2, [Li(O–NP)] with ZrCl4 affords ZrCl2(O–NP)2. Whereas previously reported zirconium bis(salicylaldiminato) complexes are typified by the trans orientation of the O-atoms, the molecular structure ZrCl2(O–NP)2 is unusual in adopting an all-cis arrangement of N, O and Cl donors. The crystal structure of the parent ligand, HOC6H3-2-But-6-CHdouble bond; length as m-dashNC6H4PPh2-3, is reported for comparison. Upon activation with methylaluminoxane the complex is highly active for the polymerisation of ethylene to oligomers and low-molecular weight polymers. Notably, the catalytic activity is unaffected by the presence of phosphine donors.