Thermosalience revealed on the atomic scale: rapid synchrotron techniques uncover molecular motion preceding crystal jumping

Abstract

The solid-state phase transformation in nickel(II) bis(diisopropyldithiocarbonate) is analyzed using a combination of high-speed in situ single-crystal diffraction, terahertz spectroscopy, optical microscopy, thermal analysis, and density functional theory. We show that the monoclinic P21/c structure of this compound undergoes a displacive phase change at about 3 °C. The monoclinic angles and unit cell volumes change reversibly between 110.3°/2265 Å3and 103.8°/2168 Å3. An analysis of atomic positions using high-resolution in situ synchrotron X-ray diffraction data revealed details of the atomic displacements that show a change in order that precedes and accompanies the change in structure. The structural changes are rapid and are manifested as reversible macroscale crystal movement and jumping (thermosalience) and represent the first case of thermosalience in dithiocarbamate complexes. © 2022 American Chemical Society.