TITANIUM DIOLATES-KETOESTERATES

Titanium methoxide (2-methyl-2,4-pentanediolate) (2,2-dimethyl-3-oxo-methylpentanoate) [Ti(OMe)(mpd)(mdop)]2

Titanium (2-methyl-2,4-pentanediolate) bis(2,2-dimethyl-3-oxo-methylpentanoate) Ti(mpd)(mdop)2

Fig. Crystal structure of [Ti(mpd)(mdop)(μ-OMe)]2

       Dimeric titanium methoxide-diolate-ketoesterate [Ti(mpd)(mdop)(μ-OMe)]2 and titanium diolate-bis(ketoesterate) Ti(mpd)(mdop)2 [where mpd = 2-methyl-2,4-pentanediolate, mdop = 2,2-dimethyl-3-oxo-methylpentanoate tBu-C(O)C-HCO-OMe] were synthesized and characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR and mass spectroscopy. The crystal structure of [Ti(mpd)(mdop)(μ-OMe)]2 was determined by single crystal XRD, it is dimer with bridging methoxide ligands (Fig.) (Crystal data:  233(2) K, a = 12.570(4) Å, b = 13.817(4) Å, c = 11.157(3) Å, β = 101.059(5)°, monoclinic, space group P21/c, Z = 2).  

    Both [Ti(mpd)(mdop)(μ-OMe)]2 and Ti(mpd)(mdop)2 are fairly stable in air as well as in solvents such as toluene and THF. They are volatile (do not leave any residue during flash evaporation at around 280 °C) and thermally stable and thus were tested as MOCVD precursors for growth of TiO2.[i]

[i] K. Woo, W.I. Lee, J.S. Lee, S.O. Kang, Inorg. Chem., 2003, 42 (7), pp 2378–2383, « Novel Titanium Compounds for Metal−Organic Chemical Vapor Deposition of Titanium Dioxide Films with an Ultrahigh Deposition Rate », DOI: 10.1021/ic0256967, https://pubs.acs.org/doi/abs/10.1021/ic0256967

[Ti(OMe)(mpd)(mdop)]2, Ti(mpd)(mdop)2 for TiO2 by MOCVD

       Ti(mpd)(mdop)(μ-OMe)]2 and Ti(mpd)(mdop)2 were applied as precursors for the growth of TiO2 thin layers by liquid-source MOCVD; they demonstrated much higher growth rate at 400−475 °C temperature (3−6 times higher), compared to commercial Ti precursors, such as Ti(mpd)(thd)2 and Ti(OPri)2(thd)2. The TiO2 film obtained using Ti(mpd)(mdop)(μ-OMe)]2 precursor was crystallised in the anatase phase and had low carbon content and smooth surface morphology.

Titanium bis-isopropoxide bis(tert-butyl-2-oxobutanoate) Ti(OiPr)2(tbob)2

      Titanium bis-isopropoxide bis(tert-butyl-2-oxobutanoate) (or titanium bis(isopropoxide) bis(tert-butylacetocetate)) Ti(OiPr)2(tbob)2 was reported to be useful as MOCVD precursor for Ti-containing layers. Vapour pressure and enthalpy of sublimation of Ti(OiPr)2(tbob)2 was determined by variable temperature thermogravimetric/differential thermogravimetric (TG/DTG) (method based on the Langmuir equation), and Ti(OiPr)2(tbob)2 (and for comparison its titanyl analogue [TiO(tbob)2]2) were evaluated as potential MOCVD precursor for the growth of Ti-contaning layers. The complex Ti(OiPr)2(tbob)2 was found to be more suitable as titanium MOCVD precursor.[i]

[i] G.V. Kunte, S.A. Shivashankar, A.M. Umarji, Meas. Sci. Technol., 2008, 19, 025704, doi:10.1088/0957-0233/19/2/025704, « Thermogravimetric evaluation of the suitability of precursors for MOCVD », http://iopscience.iop.org/0957-0233/19/2/025704

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