Mn-containing paramagnetic conductors with bis(Ethylenedithio)tetrathiafulvalene (bedt-ttf)

Abstract

Two novel paramagnetic conductors have been prepared with the organic donor bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF = ET) and paramagnetic Mn-containing metallic complexes: κ′-ET4[KMnIII (C2O4)3]·PhCN (1) and ET[MnIICl4]·H2O (2). Compound 1 represents the first Mn-containing ET salt of the large Day’s series of oxalato-based molecular conductors and superconductors formulated as (ET)4[AM(C2O4)3]·G (A+ = H3O+, NH+4, K+, …; MIII = Fe, Cr, Al, Co, …; G = PhCN, PhNO2, PhF, PhCl, PhBr, …). It crystallizes in the orthorhombic pseudo-κ phase where dimers of ET molecules are surrounded by six isolated ET molecules in the cationic layers. The anionic layers contain the well-known hexagonal honey-comb lattice with Mn(III) and H3O+ ions connected by C2O2−4 anions. Compound 2 is one of the very few examples of ET salts containing ET2+. It also presents alternating cationic-anionic layers although the ET molecules lie parallel to the layers instead of the typical almost perpendicular orientation. Both salts are semiconductors with room temperature conductivities of ca. 2 × 10−5 and 8 × 10−5 S/cm and activation energies of 180 and 210 meV, respectively. The magnetic properties are dominated by the paramagnetic contributions of the high spin Mn(III) (S = 2) and Mn(II) (S = 5/2) ions.