Synthesis and thermal decomposition of a novel zirconium acetato-propionate cluster: [Zr12]

This work reports a novel Zirconium acetato-propionate complex herein called [Zr12] obtained by reaction of zirconium acetylacetonate Zr(acac)4 with propionic acid. The molecular structure has been determined by X-ray diffraction on single crystals and proposed to be [Zr12(m3-O)16(CH3CH2CO2)12(CH3CO2)8(m2- CH3CH2CO2)4]. This cluster involves oxo/hydroxo bonds in the direct surrounding of the metallic center. The decomposition of [Zr12] has been studied by thermal analysis and compared to Zr(acac)4. Its temperature of decomposition is much lower than for acetylacetonate derivative. In consequence, the formation of ZrO2 is easier from [Zr12] than from Zr(acac)4. This phenomenon highlights the influence of the molecular structure on the process of decomposition. The local surrounding of Zr in [Zr12] and in ZrO2 are very close, while it is markedly different in Zr(acac)4.This difference of environment of the metallic ions is at the origin of the huge difference of thermal behavior of both compounds.