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-Bu₂^t-2- (CH=NBu^t)C₆H₃OH] (L¹H) or [4,6-Bu₂^t-2-(CH=NBu^t) C₆H₃OSiMe₃] (L¹SiMe₃), respectively. The compounds are monomeric in solution and in the solid-state. Reactions of TiCl₄ with one equivalent of [4,6-Bu₂^t-2-(CH=NCH₂Ph) C₆H₃OH] (L²H) and [4,6-Bu₂^t-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.