Complete series of chiral paramagnetic molecular conductors based on tetramethyl-bis(ethylenedithio)-tetrathiafulvalene (TM-BEDT-TTF) and chloranilate-bridged heterobimetallic honeycomb layers

Electrocrystallization of enantiopure (S,S,S,S)- and (R,R,R,R)-tetramethyl-bis(ethylenedithio)-tetrathiafulvalene (TM-BEDT-TTF) donors, as well as the racemic mixture, in the presence of potassium cations and the tris(chloranilato)ferrate(III) [Fe(Cl<inf>2</inf>An)<inf>3</inf>]^3- paramagnetic anion afforded a complete series of chiral magnetic molecular conductors formulated as β-[(S,S,S,S)-TM-BEDT-TTF]<inf>3</inf>PPh<inf>4</inf>[K^IFe^III(Cl<inf>2</inf>An)<inf>3</inf>]·3H<inf>2</inf>O (1), β-[(R,R,R,R)-TM-BEDT-TTF]<inf>3</inf>PPh<inf>4</inf>[K^IFe^III(Cl<inf>2</inf>An)<inf>3</inf>]·3H<inf>2</inf>O (2), and β-[(rac)-TM-BEDT-TTF]<inf>3</inf>PPh<inf>4</inf>[K^IFe^III(Cl<inf>2</inf>An)<inf>3</inf>]·3H<inf>2</inf>O (3). Compounds 1-3 are isostructural and crystallize in triclinic space groups (P1 for 1 and 2, P-1 for 3) showing a segregated organic-inorganic crystal structure, where anionic honeycomb layers obtained by self-assembling of the Λ and Δ enantiomers of the paramagnetic complex with potassium cations alternate with organic layers where the chiral donors are arranged in the β packing motif. Compounds 1-3 show a molecular packing strongly influenced by the topology of the inorganic layers and behave as molecular semiconductors with room-temperature conductivity values of ca. 3 × 10^-4 S cm^-1. The magnetic properties are dominated by the paramagnetic S = 5/2 [Fe(Cl<inf>2</inf>An)<inf>3</inf>]^3- anions whose high-spin character is confirmed by magnetic susceptibility measurements. The correlation between crystal structure and conducting behavior has been studied by means of tight-binding band structure calculations which support the observed conducting properties.