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A series of mixed-ligand–titanium complexes is reported which incorporate a tridentate N-methyldiethoxoamine (mdea) ligand in conjunction with chelating diolate ligand. X-ray crystal structures of the complexes [Ti(mdea) (O-O)]2 (where O-O = OC(CH3)2C(CH3)2O (1), OC(C2H5)2C(C2H5)2O (2), OC(CH3)2CH2CH(CH3)O (3), and OC(CH3)2CH2C(CH3)2O (4)) show them to exist as dimers in the solid state, with one arm of the aminodialkoxy ligand μ-bridging two titanium centres. Solution-state 1H and 13C NMR studies concur with the solid-state structures of (1)–(4) at low temperature. The room-temperature spectra of (3) and (4) suggest that bridging bond scission and reformation occurs increasing the apparent symmetry of the complexes. Complexes (3) and (4) dissociate into monomers in the vapour phase. The influence of the diolate ligand on the bridging bond strengths is discussed.

A highly fluxional dititanium N-methyldiethoxoamine hexaisopropoxide complex was isolated from reactions of N-methyldiethanolamine with Ti(OPri)4. X-ray crystallography identified the solid state compound as the unsymmetrical complex Ti2(μ2-(OCH2CH2)2NCH3)(μ2-OPri)(OPri)5. In solution, the time-averaged structure was shown by NMR to be symmetrical. The amine function coordinates to both titanium atoms alternately, while the isopropoxide ligands exchange to maintain equal coordination numbers on both titaniums. Variable temperature NMR demonstrates that the exchange processes slow on cooling, and a spectrum consistent with the solid-state structure is apparent at –50�C.

A method for producing amino alcohol complexes of titanium from hydrated titania (α-titanic acid) is described. Thus hydrated titania was completely converted into triethanolamine and diethanolamine complexes during reaction at 120°C for 6 h. This represents a synthetic method for titanium sol–gel precursors which are free from chlorine-containing impurities. Products were characterized with assistance from 1 H and 13 C nuclear magnetic resonance spectroscopy, and electrospray mass spectrometry. A single-crystal X-ray structure of titanium bis[2,2´- (methyl-imino)ethanolate], tetragonal, space group P4 – 2 1 c, is presented. The titanium centre is coordinated by an N2O4 donor set which can be most closely described as a bifacially capped tetrahedral geometry.