Phase transition and structures of the twinned low‐temperature phases of (Et4N)[ReS4]

Abstract

The title compound, tetraethylammonium tetrathiorhenate, [(C2H5)4N][ReS4], has, at room temperature, a disordered structure in the space group P63mc (Z = 2, α‐phase). A phase transition to the monoclinic space group P21 (Z = 2, γ‐phase) at 285 K leads to a pseudo‐merohedral twin. The high deviation from the hexagonal metric causes split reflections. However, the different orientations could not be separated, but were integrated using a large integration box. Rapid cooling to 110–170 K produces a metastable β‐phase (P63, Z = 18) in addition to the γ‐phase. All crystals of the β‐phase are contaminated with the γ‐phase. Additionally, the crystals of the β‐phase are merohedrally twinned. In contrast to the α‐phase, the β‐ and γ‐phases do not show disorder. The crystal structures of three phases of [(C2H5)4N][ReS4] were determined by single‐crystal X‐ray diffraction analysis at different temperatures. image