Zirconium and titanium propylene polymerization precatalysts supported by a fluxional C 2-symmetric bis(anilide)pyridine ligand

Ian A. Tonks, Daniel Tofan, Edward C. Weintrob, Theodor Agapie, John E. Bercaw

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Titanium and zirconium complexes supported by a bis(anilide)pyridine ligand (NNN = pyridine-2,6-bis(N-mesitylanilide)) have been synthesized and crystallographically characterized. C 2-symmetric bis(dimethylamide) complexes were generated from aminolysis of M(NMe 2) 4 with the neutral, diprotonated NNN ligand or by salt metathesis of the dipotassium salt of NNN with M(NMe 2) 2Cl 2. In contrast to the case for previously reported pyridine bis(phenoxide) complexes, the ligand geometry of these complexes appears to be dictated by chelate ring strain rather than metal-ligand π bonding. The crystal structures of the five-coordinate dihalide complexes (NNN)MCl 2 (M = Ti, Zr) display a C 1-symmetric geometry with a stabilizing ipso interaction between the metal and the anilido ligand. Coordination of THF to (NNN)ZrCl 2 generates a six-coordinate C 2-symmetric complex. Facile antipode interconversion of the C 2 complexes, possibly via flat C 2v intermediates, has been investigated by variable-temperature 1H NMR spectroscopy for (NNN)MX 2(THF) n (M = Ti, Zr; X = NMe 2, Cl) and (NNN)Zr(CH 2Ph) 2. These complexes were tested as propylene polymerization precatalysts, with most complexes giving low to moderate activities (10 2-10 4 g/(mol h)) for the formation of stereoirregular polypropylene.

Original languageEnglish (US)
Pages (from-to)1965-1974
Number of pages10
JournalOrganometallics
Volume31
Issue number5
DOIs
StatePublished - Mar 12 2012

Fingerprint Dive into the research topics of 'Zirconium and titanium propylene polymerization precatalysts supported by a fluxional C <sub>2</sub>-symmetric bis(anilide)pyridine ligand'. Together they form a unique fingerprint.

Cite this