Enantiopure and racemic radical-cation salts of B(mandelate)₂⁻ and B(2-chloromandelate)₂⁻ anions with BEDT-TTF

Abstract

Chiral and racemic BEDT-TTF salts with spiroborate anions [B(mandelate)2]− and [B(2-chloromandelate)2]−, where helical crystals are obtained when using spiroborate anions with enantiopure ligands.

Chiral Crystals, Jack, Conductivity and Magnetism

“…Wallis, in collaboration with Martin and Akutsu, [19] continued to prepare conductors made from enantiopure charge transfer salts, and his work in the area has continued until the present day. [20] In this instance just cited, chiral crystal symmetry was ensured by chiral mandelate counterions, but Wallis studied many dozens of crystals built from chiral TTF donors, e. g. Figure 1,i, derived from the original strategy he pursued with Dunitz. This work was reviewed with Avarvari, [21] who made equal and independent contri-butions to the study of conducting chiral crystals, and also collaborated with Wallis.…”

“…The eMChA effect is a change in resistivity in a chiral material on directing an applied magnetic field along or against a current in a chiral wire, whether chiral at the level of the space group symmetry or because the sample was twisted as in the case of bismuth. [20] Wagnière and Rikken made use of symmetry arguments to insist on a reciprocal effect, inverse electrical magnetochiral anisotropy. [34] Here, in a chiral conductor, a current will produce a magnetic field that does not surround a wire as required by Ampère, but rather is directed parallel to the current.…”

Chiral Spiro‐Tetrathiafulvalenes: Synthesis, Chiroptical Properties, Conformational Issues and Charge Transfer Complexes

“…[17][18][19][20][21] Alternatively, chiral counterions can be used in combination with achiral TTF donors to provide enantiopure conductors. [11,[22][23][24] Nevertheless, eMChA has been observed so far only in one pair of TTF based crystalline enantiomeric conductors, namely (DM-EDT-TTF) 2 ClO 4 (DM-EDT = dimethyl-ethylenedithio), [25] while CISS was very recently detected with the DM-BEDT-TTF and TM-BEDT-TTF (TM = tetramethyl) precursors by electrochemical measurements. [26] It is therefore of great importance to address different types of chirality in the TTF precursors in order to: i) allow access to a large library of chiral conductors which can show exotic chirality related phenomena; ii) correlate the type of chirality, chiroptical response and the magnitude of the eMChA/CISS effects.…”

“…Such compounds have been used as precursors for various conducting radical cation salts or charge transfer (CT) complexes as enantiopure and/or racemic forms [17–21] . Alternatively, chiral counterions can be used in combination with achiral TTF donors to provide enantiopure conductors [11,22–24] . Nevertheless, eMChA has been observed so far only in one pair of TTF based crystalline enantiomeric conductors, namely (DM‐EDT‐TTF) 2 ClO 4 (DM‐EDT=dimethyl‐ethylenedithio), [25] while CISS was very recently detected with the DM‐BEDT‐TTF and TM‐BEDT‐TTF (TM=tetramethyl) precursors by electrochemical measurements [26] .…”