Phase polymorphism of [Zn(DMSO)6](ClO4)2 studied by differential scanning calorimetry

Four solid phases of [Zn(DMSO)6](ClO4)2 have been detected by differential scanning calorimetry (DSC). Specifically, the phase transitions were detected between: metastable phase KII ↔ supercooled phase K0 at TC3h=315 K, stable phase KIb ↔ stable phase KIa at TC2h=341 K, stable phase KIa ↔ stable phase K0 at TC1h=355 K. At Tm2 = 389 K crystals partially and at Tm1 = 465 K completely melts. From the entropy change values it was concluded that the phases: K0 and K0′ are the orientationally dynamically disordered phases, so called ODDIC crystals, and phases KIa, KIb and metastable KII are dynamically ordered but with some degree of positional disorder.