Thermochromic behavior and phase transition of new octanuclear polyiodobismuth(III)ate

•New octanuclear iodobismuthate TBA4[Bi8I28] was synthesized.•Complex TBA4[Bi8I28] is thermochromic.•Complex has a thermal anomaly at 237 K which can be considered as a phase transition.

A new isomer of octanuclear polyiodobismuth(III)ate, (Bu4N)4[Bi8I28] (1) was obtained and characterized. The compound is characterized by a thermal anomaly at 237 K which can be related to thermochromism. The nature of the anomaly was investigated by a combination of X-ray diffractometry at different temperatures, differential scanning calorimetry and the Bader’s topological analysis of the electron density and interpreted as a phase transition. The role of intramolecular I…I contacts in the phase transition is discussed.

Graphical abstractOctanuclear iodobismuthate complex [Bi8I28]4− has been obtained. The compound is characterized by a thermal anomaly at 237 K which can be related to thermochromism. The nature of the anomaly was investigated by a complex of methods. The role of intramolecular I…I contacts in the phase transition is discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide