TITANIUM DIOLATES -AMINOALKOXIDES

Titanium ethyleneglycolate bis(dimethylamonoethoxide) [Ti(OCH2CH2O)(dmae)2]2

Fig. Dimeric crystal structure of [Ti(OCH2CH2O)(dmae)2]2

    Titanium ethyleneglycolate bis(dimethylamonoethoxide) [Ti(OCH2CH2O)(dmae)2]2 was shown to have dimeric binuclear centrosymmetric structure with bridging alkoxide groups, containing two six-coordinate Ti atoms in distorted octahedral environments. In [Ti(OCH2CH2O)(dmae)2]2 the oxygen from the ethylene glycolate ligand is involved in bridging (not from dmae ligand).

     [Ti(OCH2CH2O)(dmae)2]2 was tested as Ti MOCVD precursor, however it failed to deposit TiO2 in a reproducible fashion, what was attributed to an intramolecular disproportionation reaction leading to pre-deposition of involatile polymeric [Ti(OCH2CH2O)2]n species.[i]

 [i] A.C. Jones, P.A. Williams, J.F. Bickley, A. Steiner, H.O. Davies, T.J. Leedham, A. Awaluddin, M.E. Pemble, G. W. Critchlow, J. Mater. Chem., 2001, 11, 1428, « Synthesis and crystal structures of two new titanium alkoxy–diolate complexes. Potential precursors for oxide ceramics », https://pubs.rsc.org/en/content/articlelanding/2001/jm/b100411p/unauth#!divAbstract

Titanium (2,3-dimethylbutane-2,3-diolate) bis (dimethylaminoethoxide) [Ti(OCMe2CMe2O)(dmae)2]2

Fig. Crystal structure of [Ti(OCMe2CMe2O)(dmae)2]2

    Titanium (2,3-dimethylbutane-2,3-diolate) bis (dimethylaminoethoxide) [Ti(OCMe2CMe2O)(dmae)2]2 has as well dimeric binuclear centrosymmetric structure with two six-coordinate Ti atoms in distorted octahedral environments (with bridging alkoxide groups) (Fig.) - structure similar to its ethylenegylcolate analog [Ti(OCH2CH2O)(dmae)2]2, but in [Ti(OCMe2CMe2O)(dmae)2]2 the oxygen from dmae ligands is involved in bridging (not from the diolate ligand, like is Ti(OCH2CH2O)(dmae)2]2.[i]

[i] A.C. Jones, P.A. Williams, J.F. Bickley, A. Steiner, H.O. Davies, T.J. Leedham, A. Awaluddin, M.E. Pemble, G. W. Critchlow, J. Mater. Chem., 2001, 11, 1428, « Synthesis and crystal structures of two new titanium alkoxy–diolate complexes. Potential precursors for oxide ceramics », https://pubs.rsc.org/en/content/articlelanding/2001/jm/b100411p/unauth#!divAbstract 

[Ti(OCMe2CMe2O)(dmae)2]2 for TiO2 by MOCVD

        [Ti(OCMe2CMe2O)(dmae)2]2 was investigated as precursor for the growth of TiO2 layers by liquid injection MOCVD. Reproducible deposition of TiO2 in the temperature range 325–450 °C was achieved. However, it was reported to have no particular advantages of [Ti(OCMe2CMe2O)(dmae)2]2 as titanium MOCVD precursor compared to the conventional [Ti(OPri)2(thd)2] precursor. [i]

[i] A.C. Jones, J. Mater. Chem., 2002, 12, 2576–2590, « Molecular design of improved precursors for the MOCVD of electroceramic oxides », DOI: 10.1039/b202675a, http://www.chimica.unipd.it/gianandrea.rizzi/privata/documentazione/insegnamenti/Laboratorio%20di%20Preparazione%20e%20Caratt.%20dei%20Materiali%20I/TiO2_CVD.pdf 

Titanium (2-methylpentane-2,4-diolate) bis (dimethylaminoethoxide) [Ti(mpd)(dmae)2]2

     Titanium (2-methylpentane-2,4-diolate) bis (dimethylaminoethoxide) [Ti(OCH(Me)CH2C(Me)2O)(dmae)2]2   (or [Ti(mpd)(dmae)2]2 ) was synthesized and characterized. The complex was reported to be dimeric in the solid state with a similar structure to [Ti(OCMe2CMe2O)(dmae)2]2.

     [Ti(mpd)(dmae)2]2 was applied as Ti precursor for direct liquid injection CVD growth of TiO2 (and compared to conventional precursor Ti(OPri)4). The use of [Ti(mpd)(dmae)2]2 allowed to extend the available temperature window for growth, while producing TiO2 layers in which the proportion of anatase to rutile varied with growth conditions. Rutile phase formation with [Ti(mpd)(dmae)2]2 precursor was favoured at higher growth temperatures than with Ti(OPri)(4), and by use of O2 as constituent gas. The addition of O2 reduced the growth rate significantly, but also improved the morphology of the film (by AFM).[i]

 [i] A.Awaluddin, M.E. Pemble, A.C. Jones, P. Williams, J. Phys. IV (Proc.), 2001, 11(3), Direct liquid injection MOCVD growth of TiO2 films using the precursor Ti(mpd)(dmae)2, DOI: 10.1051/jp4:2001367,  www.researchgate.net/publication/243384312_Direct_liquid_injection_MOCVD_growth_of_TiO_2_films_using_the_precursor_Timpddmae_2

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