Dual-function molecular crystal containing the magnetic chain anion [FeIII(C2O4)Cl2-]n

We report on the structural, optical, electrical and magnetic properties of the charge-transfer salts of TTF (TTF = tetrathiafulvalene) and BETS (BETS = bis(ethylenedithio)tetraselenafulvalene) with the magnetic chain anion [FeIII(C2O4)Cl2-]n. They have been synthesized by diffusion and electrocrystallization, respectively. The structures from single-crystal X-ray diffraction reveal one-dimensional anions separated by either dimers of TTF+ or κ-type layers of BETS0.5+. Infrared reflectivity and electrical conductivity measurements on single crystals are in good agreement with those of an insulator for TTF and a metal for BETS, as the calculated band-structures predict. Interestingly, the former exhibits π–d interaction leading to a long-range Néel state below 20 K with a small canting of the moments. Similar anomaly is seen below 5 K for the BETS salt which is metallic to 2 K, thus a weak-ferromagnetic conductor.

Graphical abstractWe report on the structural, optical, electrical and magnetic properties of the charge-transfer salts of TTF (TTF = tetrathiafulvalene) and BETS (BETS = bis(ethylenedithio)tetraselenafulvalene) with the magnetic chain anion [FeIII(C2O4)Cl2-]n. They have been synthesized by diffusion and electrocrystallization, respectively. The structures from single-crystal X-ray diffraction reveal one-dimensional anions separated by either dimers of TTF+ or κ-type layers of BETS0.5+. Infrared reflectivity and electrical conductivity measurements on single crystals are in good agreement with those of an insulator for TTF and a metal for BETS, as the calculated band-structures predict. Interestingly, the former exhibits π–d interaction leading to a long-range Néel state below 20 K with a small canting of the moments. Similar anomaly is seen below 5 K for the BETS salt which is metallic to 2 K, thus a weak-ferromagnetic conductor.Figure optionsDownload full-size imageDownload as PowerPoint slide