Preparation of Heteroleptic Tin(IV) N,O-β-Heteroarylalkenolate Complexes and Their Properties as PI-MOCVD Precursors for SnO2 Deposition: Preparation of Heteroleptic Tin(IV) N,O-β-Heteroarylalkenolate Complexes and Their Properties as PI-MOCVD Precursors for SnO2 Deposition

We have successfully prepared and structurally characterized five novel tin(IV) heteroleptic N,O-beta-heteroarylalkenolates containing -CF3 groups. The synthetic route used reactions of Sn(OtBu)(4) with 3,3,3-trifluoro(pyridin-2-yl)propen-2-ol (PyTFPH), 3,3,3-trifluoro(dimethyl-1,3-oxazol-2-yl)propen-2-ol (DMOTFPH), and 3,3,3-trifluoro(1,3-benzthiazol-2-yl)propen-2-ol (BTTFPH) in dry aprotic solvents leading to elimination of tert-butanol and formation of Sn(OtBu)(2)(PyTFP)(2) (1), Sn(OtBu)(2)(DMOTFP)(2) (2), and Sn(OtBu)(2)(BTTFP)(2) (3). The chelating ligands employed a bidentate N boolean AND O donor set. The reactivity of OtBu groups in the obtained Sn(OtBu)(2)(N boolean AND O)(2) complexes was further investigated in reactions with fluorinated alcohols, 2,2,2-trifluoroethanol (TFEH) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFPH). Two complexes Sn(TFE)(2)(DMOTFP)(2) (4) and Sn(HFP)(2)(PyTFP)(2) (5) were obtained and structurally characterized. Thermal behavior of complexes 1-5 was studied by thermogravimetry and differential scanning calorimetry (TG/DSC). The most volatile compounds Sn(OtBu)(2)(PyTFP)(2) (1) and Sn(OtBu)(2)(DMOTFP)(2) (2) were chosen and tested in a PI-MOCVD process for the SnO2 growth on sapphire-C substrates. Film growth rates at different temperatures (500-900 degrees C), crystalline quality, surface roughness, transparency in UV/Vis-mid-IR spectral ranges have been investigated. The results showed that these two compounds are suitable precursors for MOCVD deposition of high quality SnO2 films. Fabricated films displayed good response to CO and NO2 in chemo-resistive gas sensing measurements.