Zero area thermal expansion of honeycomb layers via double distortion relaxation in (PPh4)[Cu2(CN)3]

Abstract

The zero area thermal expansion (TE) of a cyanide-bridged honeycomb layer was demonstrated by (PPh₄)[Cu₂(CN)₃] (PPh₄⁺ = tetraphenyl phosphonium) via double distortion relaxation. This characteristic TE behaviour involves in-plane anisotropy of the distorted layer with positive and negative TE. The conformation change in distorted PPh₄⁺ tetrahedrons also occurred between the layers. This was coupled with the anisotropic TE of the layers in accordance with complementary structural changes in the cation and anion counterparts.