Titanium complexes based on pyridine containing dialcohols: Effect of a ligand

•O,N,N,O-type ligand, 2,2′-bipy-6,6′-(CH2Ph2OH)2, gives titanyl complex.•Rare example of Ti complex with TiO bond is obtained.•Titanium complexes based on substituted 2,6-bis(hydroxyalkyl)pyridines are obtained.•Titanium complexes are active initiators of ROP of lactones.

Substituted 2,6-bis(hydroxyalkyl)pyridines, H2L, 1–3 (2,6-Py(CH2(X)OH)(CH2(Y)OH), X = Y = cyclo-C6H10, 1; X = Y = 1-Ad, 2; X = CPh2, Y = CH2CPh2, 3), were used as ligands for the synthesis of titanium(IV) complexes, (i-PrO)2Ti(L), 1a–3a. On the contrary, application of related dialcohol based on 2,2′-bipyridine, H2L′, 5 (2,2′-bipy-6,6′-(CH2Ph2OH)2), resulted in titanyl complex, (L′)TiO, 6. The molecular structure of 6 was investigated by X-ray analysis. Compounds 1a and 3a were tested as initiators in ring-opening polymerization of l-lactide and ε-caprolactone showing moderate activity.

Graphical abstractThe structure of the ligand determines the nature of the titanium complex formed. Substituted 2,6-bis(hydroxyalkyl)pyridines give typical complexes. On contrary, (2,2′-bipy-6,6′-(CH2Ph2OH)2) results in complex with TiO bond.Figure optionsDownload full-size imageDownload as PowerPoint slide