Synthesis, structures, dynamics, and olefin polymerization behavior of group 4 metal (pyCAr2O)2M(NR2)2 complexes containing bidentate pyridine-alkoxide ancillary ligands

Il Kim, Yasushi Nishihara, Richard F. Jordan, Robin D. Rogers, Arnold L. Rheingold, Glenn P.A. Yap

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Abstract

The reaction of 2-lithiopyridine and the appropriate diarylketone followed by hydrolysis yields pyCAr2OH pyridine-alcohols (1a, Ar = 4-tBu-C6H4; 1b, pyCAr2OH = 2-pyridyl-9-fluorenol; 1c, Ar = 3-CF3-C6H4; 1d, Ar = 4-Ph-C6H4; 1e, Ar = 4-NEt2-C6H4; 1f, pyCAr2-OH = 1-(2-pyridyl)-1-dibenzosuberol; 1g, Ar = 3,5-(CF3)2-C6H3). The reaction of Ti(NMe2)4 with 2 equiv of 1a-g yields (pyCAr2O)2Ti(NMe2)2 (2a-g) and NMe2H. The reaction of Zr-(NMe2)4 with 2 equiv of 1a,b,e yields (pyCAr2O)2Zr(NMe2)2 (3a,b,e), while similar reactions with 1c,d yield mixtures of (pyCAr2O)xZr(NMe2)4-x (x = 1-3) species. {pyC(3-CF3-C6H4)2O} 3-Zr(NMe2) (4c) and {pyC(4-NEt2-C6H4)2O}4Zr (5e) are prepared from Zr(NMe2)4 and 3 equiv of 1c or 4 equiv of 1e, respectively. The reaction of Hf(NMe2)4 with 2 equiv of 1a,e yields (pyCAr2O)2Hf(NMe2)2 (6a,e), while reaction with 3 equiv of 1b,c yields (pyCAr2O)3Hf(NMe2) (7b,c). X-ray crystallographic analyses establish that 2b, 2e, and 3a adopt distorted octahedral structures with a trans-O, cis-py, cis-amide arrangement of ligands. NMR data show that (pyCAr2O)2M(NMe2)2 complexes adopt the same structure in solution but undergo inversion of configuration at the metal with racemization barriers (ΔG‡ (racemization)) in the range of 12-14 kcal/mol. Treatment of (pyCAr2O)2M(NMe2)2 complexes with Al(iBu)3 and methylalumoxane (MAO) yields active, multisite ethylene polymerization catalysts.

Original languageEnglish
Pages (from-to)3314-3323
Number of pages10
JournalOrganometallics
Volume16
Issue number15
Publication statusPublished - Jul 22 1997
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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