Yttrium –Diketonate Glyme MOCVD Precursors: Effects of the Polyether Length on Stabilities, Mass Transport and Coordination Sphere

The glyme adducts of trishexafluoroacetylacetonato yttrium, [Y(hfa)3.monoglyme], [Y(hfa)3.diglyme], [Y(hfa)3.(H2O)2.triglyme] and [Y(hfa)2.tetraglyme]+ [Y(hfa)4]- {CH3(OCH2CH2)nOCH3, n = 1 monoglyme, 2 diglyme, 3 triglyme and 4 tetraglyme}, were synthesized and characterized by elemental analysis, mass spectrometry, and IR, 1H and 13C NMR spectroscopy. Additionally, [Y(hfa)3.monoglyme] and [Y(hfa)3.diglyme] were characterized by single-crystal X-ray diffraction studies. The mass-transport properties of these adducts were investigated by thermogravimetric analysis, differential scanning calorimetry, evaporation-rate measurements and chemical vapour-deposition experiments. There is evidence of high volatility and very good thermal stabilities with a residue lower than 2 - 4 %. Vaporization-rate experiments proved that all adducts are well-suited for metal-organic chemical vapour-deposition experiments. The [Y(hfa)3 monoglyme] complex was successfully applied in the low-pressure MOCVD process of YBaCuO HTc superconductor using a multimetal molten single source.