Barium and titanium aryl oxides as precursors for the preparation of thin-film oxides. The effect of bombardment by O ₂ ⁺

A set of barium aryl oxides of composition [Ba(OC6H2But2-2,6-X-4)2(thf)n](X = H 1, Me 2, OMe 3 or But4; thf = tetrahydrofuran) has been prepared together with the related adducts [Ba(OC6H2But2-2,6-X-4)2{P(NMe2)3O}2](X = H 5 or Me 6), which can be obtained by treating compounds 1 and 2 with neat P(NMe2)3O respectively. X-Ray studies showed that 6 has a distorted-tetrahedral structure, with the two Ba–O bonds to the aryl oxide ligands somewhat shorter than those to the P(NMe2)3O groups [2.414(8)vs. 2.579(8)Å]. Samples of complex 4 and [Ti(OC6H3Pri2-2,6)4], respectively, and a third homogeneous sample obtained by mixing equimolar amounts of these have been subjected to bombardment by Ar+ and O2+ ions of relatively low energy (3.5 keV) and the ensuing transformation investigated by X-ray photoelectron spectroscopy. No significant variation of the C/M ratio was observed when employing Ar+ ions, but O2+ produced a remarkable decrease in the carbon content which leads eventually to the formation of inorganic compounds, BaCO3, TiO2 and BaTiO3, respectively, for the three samples. Action of oxygen plasma on the titanium aryl oxide did not result in a marked decrease in the C/M ratio, but it produced instead high concentrations of carbon- and oxygen-containing species.