Methyltriskaidecazirconates, Molecular Forms of Zirconia

Repeated methanolysis of [Zr3O](OPrn)10 followed by extraction and crystallization from toluene yields material that is X-ray crystallographically indistinguishable from the compound previously formulated as [Zr13O8](OMe)36. Elemental analysis and 1H solution NMR spectroscopy strongly suggest that this material is a mixture of methyltriskaidecazirconates (MTZ) [Zr13O8](OMe)x(OH)36-x, xav ∼ 20, that readily cocrystallize from hydrocarbon solution. These species have the metal−oxygen framework structure reported for [Zr13O8](OMe)36, where the 13 zirconium and 32 bridging oxygen atoms comprise a fragment of the fluorite structure adopted by ZrO2 at elevated temperatures. Ethanolysis of [Zr3O](OPrn)10 yields its ethyl analogue, [Zr3O](OEt)10. Both trizirconates display temperature-dependent 1H solution NMR spectra that are interpreted mechanistically in terms of rearrangement mechanisms involving trigonal twists at the octahedral zirconium centers

Isolation and Structural Characterization of Tetra-<i>n</i>-propyl Zirconate in Hydrocarbon Solution and the Solid State

Tetra-n-propyl zirconate has been purified by vacuum distillation and isolated as an extremely moisture sensitive, crystalline solid. According to a single-crystal X-ray diffraction study, crystalline tetra-n-propyl zirconate is composed of tetrameric Zr4(OPrn)16 (1) molecules whose Zr4O16 metal−oxygen core structure has virtual C2h symmetry, the same structure observed previously for n-alkyl orthotitanates. Carbon-13 NMR spectroscopic data indicate that this core structure is retained in hydrocarbon solution. Molecule 1 has the same M4O16 metal−oxygen core structure as [CH3C(CH2O)3]2M4(OPri)10, M = Ti, where the metal centers have octahedral coordination geometry, but a metal−oxygen core structure different from that of the M = Zr case, where trigonal metaprismatic coordination geometry is observed

Isolation and Structural Characterization of Tetra-<i>n</i>-propyl Zirconate in Hydrocarbon Solution and the Solid State

Tetra-n-propyl zirconate has been purified by vacuum distillation and isolated as an extremely moisture sensitive, crystalline solid. According to a single-crystal X-ray diffraction study, crystalline tetra-n-propyl zirconate is composed of tetrameric Zr4(OPrn)16 (1) molecules whose Zr4O16 metal−oxygen core structure has virtual C2h symmetry, the same structure observed previously for n-alkyl orthotitanates. Carbon-13 NMR spectroscopic data indicate that this core structure is retained in hydrocarbon solution. Molecule 1 has the same M4O16 metal−oxygen core structure as [CH3C(CH2O)3]2M4(OPri)10, M = Ti, where the metal centers have octahedral coordination geometry, but a metal−oxygen core structure different from that of the M = Zr case, where trigonal metaprismatic coordination geometry is observed