Synthesis, structural determination, and ethylene polymerization chemistry of mono(salicylaldiminato) complexes of titanium(IV)

Titanium(IV)mono(salicylaldiminato) complexes [L1Ti(NMe2)3] (1) and [L1TiCl3] (2) have been synthesized by treatment of Ti(NMe2)4 or TiCl4 with one equivalent of [4,6-Bu2t-2-(CHNBut)C6H3OH] (L1H) or [4,6-Bu2t-2-(CHNBut)C6H3OSiMe3] (L1SiMe3), respectively. The compounds are monomeric in solution and in the solid-state. Reactions of TiCl4 with one equivalent of [4,6-Bu2t-2-(CHNCH2Ph)C6H3OH] (L2H) and [4,6-Bu2t-2-{CHN(2-C6H4OH)}C6H3OH] (L3H2) produced [L2TiCl2(μ-Cl)]2 (3) and [L3TiCl2]2 (4), respectively. [L3TiCl2(THF)] (5) was also produced in quantitative yield when 4 was stirred in THF for 16 h. The reaction of TiCl4 with L3H2 (Two equivalents) in toluene gave [(L3)2Ti] (6). The molecular structures of 2–4 and 6 were established by single-crystal X-ray diffraction studies; and 4 displayed a rare face to face π–π stacking interaction in its structure. Compounds 1 and 2 showed modest ethylene polymerization activities at 25 °C with 900 molar equivalents of methylalumoxane (MAO) as co-catalyst.