Phase Transitions in Three New Hybrid Crystals: (Me3NR)4[Ni(NCS)6] (R=Ethyl, Propyl, and Butyl)

Understanding the microscopic origin of phase transitions in hybrid crystals is of significant important but challenging for designing novel phase-transition materials. Here, three new hybrid crystals, (Me3NR)(4)[Ni(NCS)(6)] (R=ethyl for 1, propyl for 2, and butyl for 3) were synthesized and comprehensively studied on their crystal structures, intermolecular interactions, and phase transitions. They possess a same anti-XeF4 structure mode but exhibit different phase transitions arising from their subtly changed alkyl groups. Specifically, 1 undergoes four-step P2(1)/c-P2(1)/c-P2(1)/c-Pbca-Cmce crystalline transitions at 165, 203, 244, and 280 K, respectively; 2 undergoes three-step P2(1)2(1)2(1)-Pbca-P2(1)/n-P 3? ${\bar 3}$ 1c crystalline transitions at 167, 393, and 410 K, respectively, following by a solid-liquid transition at 453 K; 3 undergoes an iso-space-group P2(1)/n-P2(1)/n crystalline phase transition at 257 K and a solid-liquid transition at 410 K. These instances well demonstrate the key roles of delicate and complicated intermolecular interactions on inducing nontrivial phase transitions in hybrid crystals.

Automated summary

Understanding the microscopic origin of phase transitions in hybrid crystals is crucial but challenging. This study synthesized three new hybrid crystals and comprehensively studied their crystal structures, intermolecular interactions, and phase transitions. The results demonstrate the importance of delicate and complicated intermolecular interactions in inducing nontrivial phase transitions in hybrid crystals.