Syntheses, reactions, and ethylene polymerization of titanium complexes with [N,N,S] ligands

Abstract

Tridentate dianionic arylsulfide free ligands [ArNHCH(2)C(6)H(4)NHC(6)H(4)-2-SPh] (Ar = Ph (3a); Ar = 2,4,6-trimethylphenyl (3b); Ar = 2,6-diisopropylphenyl (3c)) have been prepared by reduction of the corresponding imine compounds [ArN[double bond, length as m-dash]CHC(6)H(4)NHC(6)H(4)-2-SPh] (Ar = Ph (2a); Ar = 2,4,6-trimethylphenyl (2b); Ar = 2,6-diisopropylphenyl (2c)) with LiAlH(4) in high yields. Reactions of TiCl(4) with the tridentate dianionic arylsulfide free ligands (3a-3c) afford five-coordinate and four-coordinate titanium complexes [κS, κ(2)N-(ArNHCH(2)C(6)H(4)NHC(6)H(4)-2-SPh)TiCl(2)] (Ar = Ph (4a); Ar = 2,4,6-trimethylphenyl (4b)] and [κ(2)N-(ArNHCH(2)C(6)H(4)NHC(6)H(4)-2-SPh)TiCl(2)] (Ar = 2,6-diisopropylphenyl (4c)], respectively. The molecular structures of compounds 2b, 2c, 3b and 3c·HCl have been characterized by single crystal X-ray diffraction analyses. Complexes 2a-4c are characterized by IR,(1)H-NMR spectra, and elemental analysis. EXAFS spectroscopy performed on complexes 4b and 4c reveals the expected different coordination geometry due to steric hindrance effect. When activated by excess methylaluminoxane (MAO), 4a-4c can be used as catalysts for ethylene polymerization and exhibit moderate to good activities.