The structural behaviour of homoleptic xenon difluoride (XeF 2 ) complexes M (XeF 2 ) 6 SbF 6 2 ( M = Cu, Zn) under varying temperature and pressure has been investigated, aiming to resolve the disordered Jahn–Teller distortions in the copper complex ( CuSb ). At 200 K, both CuSb and its zinc analogue ( ZnSb ) crystallize in a layered CdCl 2 -type structure with the space group R 3 . Upon cooling below 170 ( CuSb ) and 160 K ( ZnSb ), both systems transition to isostructural phases in P 1 , with CuSb assuming an ordered Jahn–Teller distortion. The transformation is driven by the shortening and optimization of the Xe...F intermolecular contacts, forming stronger and more directional interactions, rather than by Jahn–Teller effects alone. This is supported by the observation of similar transitions in the Jahn–Teller-inactive Zn system. High-pressure experiments up to ∼2.8 GPa at room temperature show the structural stability of the high-symmetry phases, implicating kinetic barriers to further transformation. Additionally, the synthesis and structural characterization of a novel arsenic analogue, Zn(XeF 2 ) 6 AsF 6 2 ( ZnAs ), reveal similar layered motifs but distinct phase behaviour. Symmetry-mode analyses relate all observed phases through distortions of a common CdCl 2 aristotype.
Clough et al. (Thu,) studied this question.