Singular Crystalline β‘-Layered Topologies Directed by Ribbons of Self-Complementary Amide···Amide Ring Motifs in [EDT-TTF-(CONH2)2]2X (X = HSO4-, ClO4-, ReO4-, AsF6-): Coupled Activation of Ribbon Curvature, Electron Interactions, and Magnetic Susceptibility

Abstract

The deliberate design of a series of single crystals of conducting two-dimensional radical cation salts of o-bis(amide)-appended ethylenedithiotetrathiafulvalene, β‘-[EDT-TTF-(CONH₂)₂]₂X (X = HSO₄^-, ClO₄^-, ReO₄^-, or AsF₆^-) and of their parent monocomponent solid EDT-TTF-(CONH₂)₂ is demonstrated and allows us to reach a level of prediction of the structure of molecular conductors. Their conductivity is activated with a gap of 1650 K and a sizable room-temperature conductivity of 0.15 S·cm^-1 (for X = ClO₄^-) and a singular spin susceptibility for a β‘-type salt that, in addition, changes very remarkably with the anion. The key design element is that of a recurrent, puckered ribbon constructed out of self-complementary, hydrogen-bonded amide···amide ring motifs whose minute modulations of curvature and shape throughout the series have been shown to correlate to very remarkable differences in the intrastack β_HOMO-HOMO interaction energies and changes in the density of states at the Fermi level and on to important differences of spin susceptibility behavior in a system where electron correlations are significant. The coupled activation of structure, electron interactions, and magnetic susceptibility discovered and discussed throughout the paper is unprecedented and is seen as a genuine expression of interfacial hydrogen-bond interactions onto the collective electronic properties.