Solution routes to lead titanate: synthesis, molecular structure and reactivity of the Pb–Ti and Pb–Zr species formed between various lead oxide precursors and titanium or zirconium alkoxides. Molecular structure of Pb2Ti2(µ4 -O)(OAc)2(OPri)8 and of PbZr3(µ4-O)(OAc)2(OPri) 10

Abstract

The reactions between Ti(OR) ₄ (R=Et, Pr ⁱ ) or [Zr(OPr ⁱ ) ₄ (Pr ⁱ OH)] ₂ and various lead oxide precursors [anhydrous Pb(OAc) ₂ , alkoxides or oxoalkoxides] have been investigated in different experimental conditions (solvent, temperature). Various mixed-metal species have been isolated in high yields and characterized by microanalysis, FTIR and multinuclear NMR ( ¹ H, ¹³ C and ²⁰⁷ Pb) spectroscopies. The mixed-metal oxoacetatoalkoxides Pb ₂ Ti ₂ (µ ₄ -O)(µ-OAc) ₂ (µ-OPr ⁱ ) ₅ (OPr ⁱ ) ₃ 1 and PbZr ₃ (µ ₄ -O)(µ-OAc) ₂ (µ-OPr ⁱ ) ₅ (OPr ⁱ ) ₅ 2 have been characterized by X-ray crystallography at -100 °C: for 1, monoclinic, space group C ₂ /c with a=38.916(17) Å, b=12.045(2) Å, c=19.046(4) Å, β=112.84(3)°, V=8224(4) Å ³ , Z=8, R=0.068, R _w =0.076; and for 2, monoclinic, space group P2 ₁ /n with a=10.618(2) Å, b=25.157(11) Å, c=18.611(5) Å, β=90.35(2)°, V=4971(3) Å ³ , Z=4, R=0.060, R _w =0.072. Hydrolysis–condensation reactions have been achieved especially for the species having a Pb:Ti stoichiometry appropriate for access to PbTiO ₃ . Effects of the solvent on the temperature of crystallisation and on the particle size are discussed.