Enormous lattice distortion through an isomorphous phase transition in an organic–inorganic hybrid based on haloantimonate(iii)

Abstract

BisIJdiisobutylammonium) octabromodiantimonateIJIII), [(i-C 4 H 9 ) 2 NH 2 ] 2 Sb 2 Br 8 , has been synthesized. The differential scanning calorimetric measurements indicate a reversible, first-order phase transition at 222/ 229 K (cooling/heating). The single crystal X-ray diffraction studies reveal that the phase transition is isomorphous and is accompanied by a huge distortion of the crystal lattice. By comparison of the crystal structures of [(i-C 4 H 9 ) 2 NH 2 ] 2 Sb 2 Br 8 and [(i-C 4 H 9 ) 2 NH 2 ] 2 Sb 2 Cl 8 , an analogous mechanism of the phase transition of the former is proposed. The change of the electronic structure of the complex during the phase transition was analyzed by UV-vis spectroscopy. A low-frequency dielectric relaxation process appears over phase I (below the room temperature) and corresponds to the dynamics of dipolar diisobutylammonium cations. The detailed analysis of the molecular motions of the organic cations studied by means of proton magnetic resonance ( 1 H NMR) in a wide temperature range indicates a leading role of the methyl groups in the relaxation mechanism. A variable-temperature investigation of the infrared spectra of [(i-C 4 H 9 ) 2 NH 2 ] 2 Sb 2 Br 8 confirms, in turn, the influence of the diisobutylammonium cation dynamics on the molecular mechanism of the structural transformation at 229 K.

Ferroelectricity in bis(ethylammonium) pentachlorobismuthate(iii): synthesis, structure, polar and spectroscopic properties

“…35 Of these bands, the A band centered at ∼340 nm is particularly sensitive to the geometry of the distortion of the ns 2 complex. 36 Indeed, the observed discontinuous changes in the A band maximum as well as its half width in the spectra of ECB seem to confirm this conclusion. Taking into account the structural changes, one may conclude that the more rigid structure of the anionic [BiCl 6 ] 3− complex in Phase I becomes less tight in Phase II.…”

An Above‐Room‐Temperature Phase Transition with Dielectric‐Switching Properties in a Halogenobismuthate(III) – Tris(Cyclohexylmethylammonium) Pentabromobismuthate(III) Bromide

“…Thus, it is of great significance to design and construct new functional solid‐state phase‐transition compounds . Though various strategies have been developed to construct solid‐state phase‐transition materials, the prediction and design of new high‐performance phase‐transition materials remains challenging owing to their complicated molecular interactions . Recent progress in research into solid‐state phase transitions, associated with the reorientational motion of the flexible cations in organic–inorganic hybrids, has offered a potentially effective strategy for the exploration of new phase‐transition materials .…”

Supramolecular Approach for Fine-Tuning of the Bright Luminescence from Zero-Dimensional Antimony(III) Halides

“…Such edge-sharing SbX 5 pyramids are known from the literature; however, they display no emission at RT. 43 The scenario (iii) yields compounds [C@Rb][C@Ba][SbBr 6 ] and [C@Cs][C@Ba][SbBr 6 ], crystallizing in a high symmetry space group, R a . This is due to the fact that the cumulative positive charge of 3+ from two cations is matching the negative charge of the anionic species.…”