[Ag(μ‐ <i>en</i> )][ReO ₄ ]: An Intermediate during Preparation of the Ethylene Epoxidation Catalyst

Preparation of a catalyst for the ethylene oxide production requires impregnation porous corundum support with an aqueous silver diamine oxalate complex solution, to which among others NH4[ReO4] is added. Here we report on [Ag(μ-en)][ReO4] that precipitates from such mixture. Single crystal structure analysis has revealed striking similarity [Ag(μ-en)]+ entity same cation encountered in [Ag(μ-en)]2(C2O4)×2H2O. Silver coordinated end-on nitrogen atoms en ligands. The [ReO4]− anions are not bonded cations, but instead involved N−H⋅⋅⋅O hydrogen bonds molecules. first step thermal degradation occurs at approximately temperature both, main component precipitate [Ag(μ-en)]2(C2O4)×2H2O and [Ag(μ-en)][ReO4], warranting proximity rhenium promoter elemental deposit. At 300 °C, EO synthesis commonly calcined, decomposition product plain under synthetic air Ag[ReO4], full analogy industrial manufacturing process selected Re-promoted formulations.