A cross-phase reaction coordinate in the formation of a simple copper (II) orotate complex; lability of crystals of a Jahn-Teller active intermediate

 

Isolable crystals of the cesium salt of an anionic Jahn-Teller-active Cu complex, initially formed by reaction in solution, are spontaneously consumed in a solvent-mediated crystal-to-crystal transformation that produces a final product with a four-coordinate Cu center. Depending on the size of the crystals of the intermediate and the evaporation rate of the solvent, the transformation from intermediate to final product occurs in a two-week time frame. The crystalline Jahn-Teller Cu intermediate presents a noteworthy difference in stability compared to its non-Jahn-Teller Ni-centered isomorph. It is proposed that a Jahn-Teller intermediate may precede the formation of other four-coordinate Cu complexes.