Reversible Phase Transitions and Dielectric Properties in [(CH3)4P]2[Cr2O7] and ­[Et4P]2[Cr3O10]

摘要: Tetramethylphosphonium dichromate ([(CH3)4P]2[Cr2O7], 1) undergoes a reversible phase transition at around 221 K. The results of the variable-temperature single-crystal X-ray structural analyses and rotational potential energy calculations suggest that is probably related to order–disorder [Cr2O7]2– anion. change space group from Pa-3 room temperature Pbca low reflected in peak-like dielectric response. Tetraethylphosphonium trichromate ([Et4P]2[Cr3O10], 2) crystallizes monoclinic P21/c temperature. Upon cooling heating, step-like anomalies observed 270 K indicate transition. Moreover, certify motion [Cr3O10]2– anion, being These findings open new approach design complexes show transitions coupled with unusual properties.