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

Abstract 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, (Me 3 NR) 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‐XeF 4 structure mode but exhibit different phase transitions arising from their subtly changed alkyl groups. Specifically, 1 undergoes four‐step P 2 1 / c ‐ P 2 1 / c ‐ P 2 1 / c ‐ Pbca ‐ Cmce crystalline transitions at 165, 203, 244, and 280 K, respectively; 2 undergoes three‐step P 2 1 2 1 2 1 ‐ Pbca ‐ P 2 1 / n ‐ P 1 c crystalline transitions at 167, 393, and 410 K, respectively, following by a solid‐liquid transition at 453 K; 3 undergoes an iso‐space‐group P 2 1 / n ‐ P 2 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.