In situ oxalate formation during hydrothermal synthesis of uranyl hybrid materials

The hydrothermal reaction of the uranyl cation with pyridine-, pyrazine-and pyrimidine-based organic compounds has resulted in four new and four known uranyl-organic hybrid materials that have been characterized by single-crystal and powder X-ray diffraction. Three of these materials contain the oxalate anion, formed as a result of in situ reactivity of the organic precursors. Trends in ligand reactivity have been observed and various factors that may influence oxalate formation have been explored, including time, temperature, pH and identity of the uranyl counterion. A mechanism for oxalate formation has been proposed and various methods of inhibiting in situ reactivity have been suggested.