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

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 center dot center dot center dot I contacts in the phase transition is discussed. (C) 2014 Elsevier B.V. All rights reserved.