Synthesis and Reactivity of Titanium(IV)−Salen Complexes Containing Oxygen and Chloride Ligands

The reaction of in situ-generated Ti(O i Pr) 2 (X) 2 (X = OAr, OTf) with H 2 salen or H 2 salen* yields the stable, well-characterized Ti(salen)X 2 series of complexes. Ti(salen*)(OTf) 2 could also be synthesized by reacting the previously unknown Ti(salen*)Cl 2 with TMSOTf or AgOTf. The ditriflates could be converted back to the aryloxides upon reaction with 2 equiv of NaOAr. Ti(salen)(4- tert -butyphenoxy) 2 was characterized by X-ray crystallography and found to contain a pseudoplanar salen ligand with two axially coordinated aryloxide ligands. H 2 salen and H 2 salen* were also found to cleanly react with in situ-generated Ti(O i Pr) 3 (X) (X = OC(O)R, OTf) to yield the unsymmetrically substituted Ti(salen)(O i Pr)(X) and Ti(salen*)(O i Pr)(X) complexes, respectively. In the case of X = OTf, the isopropoxide ligand could be cleanly protonated with 4- tert -butylphenol to yield Ti(salen)(OAr)(OTf) in high yield. This complex could also be accessed by the comproportionation reaction of Ti(salen)(OAr) 2 and Ti(salen)(OTf) 2 .