Chalcogen-Peierls Transition: Single-Crystal-to-Single-Crystal Transition from a Two-Dimensional to a One-Dimensional Network of Chalcogen Bonds at Low Temperature

Abstract

Abstract Due to inherent structural instability, low-dimensional materials often undergo the Peierls transition upon cooling, which is suppressed by an increase in dimensionality of their solid-state electronic structures using secondary bonding interactions such as chalcogen bonds (ChB). We revealed here that ChB themselves have an inherent structural instability when a chalcogen atom participates in simultaneous formation of two ChB, demonstrating for the first time a Peierls-like transition (chalcogen-Peierls transition) of ChB-based organic solids upon cooling. Thus, a lattice dimerization occurs at 220–230 K that changes the two-dimensional ChB network into an accumulated one-dimensional ribbon network in the tetracyanoquinodimethane fused with two [1,2,5]thiadiazoles (1). Negative cooperativity of two ChB formation is weakened on the Se atom due to greater polarizability. Thus, the selenadiazole analogues (2 and 3) undergo a similar chalcogen-Peierls transition at lower temperatures, such as at 160–170 K and at 110–120 K, respectively, depending on the number of Se atom incorporated (one or two, respectively).