Influence of the lead carboxylate on the molecular composition of its solutions with zirconium and titanium isopropoxides or n-butoxides:: 2-ethylhexanoate vs acetate, a way to stabilize the first Pb-Zr carboxylatoalkoxides of 1:1 stoichiometry

The reactions between titanium or zirconium alkoxides namely Ti(OR)(4) (R = Pr-i, Bu-n) or Zr-2((OPr)-Pr-i)(8)((HOPr)-Pr-i)(2), Zr((OBu)-Bu-n)(4) respectively and lead 2-ethylhexanoate Pb(O2CC7H15)(2) were investigated at room temperature (rt) and by heating. The various compounds were characterized by elemental analysis, FT-IR, H-1 and Pb-207 NMR. The mixed-metal species obtained at rt were adducts Pb4Zr4(mu-O2CR')(8)(OR)(16)(OHR)(2) 1 and Pb2Ti4(mu-O2CR')(4)(OR)(16) 2 (R'=CHCHEt(CH2)(2)Me, R = Pr-i) independently of the stoichiometry used. The structures of 1 and 2 are based on triangular M2Pb cores (M = Zr, Ti). with 6-coordinate transition metals -as required for perovskites- and 6- or 7-coordinate lead atoms. Similar observations were made with n-butoxides. Thermal and hydrolytic condensation reactions were investigated. Thermal condensation was more difficult for the n-butoxide derivatives than for the isopropoxide ones. Powders derived from the hydrolysis of the Single Source Precursor 1 in various conditions were characterized by TGA, XRD and SEM for the PZ ceramic.