A study on the development of CVD precursors V – syntheses and characterization of new N-alkoxy-β-ketoiminate complexes of titanium

The synthesis and characterization of various new titanium N-alkoxy-β-ketoiminate complexes are reported. Reactions between N-alkoxy-β-ketoimine ligands and Ti(O-iPr)4 resulted in dimeric [Ti(O-iPr)2(N-alkoxy-β-ketoiminate)]2 complexes or monomeric [Ti(N-alkoxy-β-ketoiminate)2] ones depending on the amount of ligands. Terdentate N-alkoxy-β-ketoiminate ligands do not prevent dimer complexes from undergoing disproportional rearrangement to produce Ti(O-iPr)4 and [Ti(N-alkoxy-β-ketoiminate)2]. The mechanism of this behavior is too complicated but it may include the dissociation and recoordination of ligands. Crystal structures of [Ti(N-alkoxy-β-ketoiminate)2] (MeC(O)CHC(Me)NC(Et)CH2O (3f) and t-BuC(O)CHC(Me)NCH2CH(Me)O (3k)) show that these are distorted octahedron and β-ketoiminate ligands appear to coordinate as a β-imino enolate. Two terdentate β-ketoiminate ligands coordinate meridionally and they are perpendicular to each other. Thermal characteristics of monomeric and dimeric titanium complexes were determined by TGA and DSC and these are reasonably volatile as potential precursors of TiO2 thin films.