Synthesis particularities, structure and properties of the radical cation salts ω-(BEDT-TTF)_5M(SCN)_6-C_2H_5OH, M = Mn, Ni

摘要

Electrochemical oxidation of donor bis(ethyienedithio)tetrathiafulvalene (BEDT-TTF) in 1,1,2-trichioroethane-ethanol in the presence of electrolytes including two type of ligands, namely, (Ph_4P)_2[M(dca)_2(SCN)_2], M = Mn, Ni; dca = [N(CN)_2]~-, has been performed and analyzed for the first time. It has been found that in the reaction of electrochemical oxidation of BEDT-TTF, [M(dca)_2(SCN)_2]~(2-) anion decomposes to form new metal-complex anions, [Mn(dca)_3(SCN)_2-H_2O]~(3-) and [Mn(SCN)_6]~(4-) or [Ni(SCN)_6]~(4-), respectively, as well as (dca) and SCN anions. New radical cation salts, (BEDT-TTF)_4Mn[(dca)_3(SCN)_2-H_2O](SCN)_x, x<1, (I), ω-(BEDT-TTF)_5M(SCN)_6-C_2H_5OH, M = Mn (III), Ni (IV), and previously described α"-(BEDT-TTF)_2(dca)-2H_2O (II) have been synthesized. A solid-phase transformation of crystals I to crystals II have been found. Crystal structure and conducting of the salts, as well as the electronic structure and magnetic properties of III, were analyzed. Salts III and IV have layered structure in which co-type radical cation layers alternate with insulating anion layers composed of [M(SCN)_6]~(4-) anions. Crystals I is a bad metal while two others exhibit a semiconducting behavior of conductivity. No exchange interactions for Mn~(2+) ions observed in the salt III.