Lee Martin

Metallic molecular crystals containing chiral or racemic guest molecules

Metallic charge-transfer salts of BEDT-TTF containing both racemic (R/S)- and chiral (S)-sec-phenethyl alcohol as guest molecules have been crystallised and their structures and physical properties are compared.

Chiral conducting salts of BEDT-TTF containing a single enantiomer of tris(oxalato)chromate(III) crystallised from a chiral solvent

Two polymorphs of a chiral conductor formulated (BEDT-TTF)3NaCr(C2O4)3·CH3NO2 have been crystallised from a solution containing the racemic anion tris(oxalato)chromate(III). In the presence of (R)-(−)-carvone the electrocrystallisation of Na3Cr(C2O4)3 with BEDT-TTF and nitromethane yields two products: hexagons crystallising in the space group P212121 (I) and needles in the space group P21 (II). Single crystal electrical transport measurements show semiconducting behavior for both salts.

A molecular charge transfer salt of BEDT-TTF containing a single enantiomer of tris(oxalato)chromate(III) crystallised from a chiral solvent

The first chiral BEDT-TTF-tris(oxalato)metallate(III) salt has been crystallised from a solution containing the racemic anion in the chiral solvent (R)-(−)-carvone.

Novel enantiopure bis(pyrrolo)tetrathiafulvalene donors exhibiting chiral crystal packing arrangements

Two novel enantiopure bis(pyrrolo[3,4-d])tetrathiafulvalene derivatives, substrates for preparing chiral conducting materials, show chiral crystal packing arrangements in which successive layers are rotated in accordance with an exact or approximate 43 axis. The corresponding donors containing fused dihydropyrrole groups, and thus four more hydrogen atoms, form stacks along a crystal axis.

Anion-cation interdependency in bedt-ttf charge transfer salts of [MIII(C2O4)]3−

Abstract Metal(III)tris(oxalate) charge transfer salts of bis(ethylenedithio)tetrathiafulvalene, bedt-ttf, display a rich variety of magnetic and conducting properties. The series contains both semiconductors and the first molecular superconductor containing paramagnetic d electrons. Most of the compounds in the series follow the general formula (bedt-ttf) 4 M(C 2 O 4 ) 3 . A.solvent (M = metal(III); A = K + , NH 4 + or H 2 O). The conducting properties arise from different arrangements of the bedt-ttf molecules; packing motifs, conformational changes and charge distribution. We examine how changes in the oxalate co-ordination mode can promote specific donor packing motifs.

Charge transfer complexes and radical cation salts of chiral methylated organosulfur donors

The single crystal X-ray structure of the all-axial conformer of the (R,R,R,R) enantiomer of the chiral donor tetramethyl-BEDT-TTF (TM-BEDT-TTF) was described and compared to the all-equatorial conformer. (S,S,S,S)-Tetramethyl-BEDT-TTF formed crystalline 1 : 1 complexes with TCNQ and TCNQ-F4, as well as a THF solvate of the TCNQ complex. Donors bis((2S,4S)-pentane-2,4-dithio)tetrathiafulvalene and (ethylenedithio)((2S,4S)-pentane-2,4-dithio)tetrathiafulvalene, which contain seven-membered rings bearing chirally oriented methyl groups, only formed complexes with TCNQ-F4. The TCNQ-F4 complexes contain planar organosulfur systems, in contrast to the TCNQ complexes in which there is minimal charge transfer. A variety of crystal packing modes were observed. Electrocrystallization experiments with both enantiomers and the racemic form of tetramethyl-BEDT-TTF afforded mixed valence radical cation salts with the AsF6 and SbF6 anions formulated as (TM-BEDT-TTF)2XF6 (X = As, Sb). Electrical conductivity was only found in one charge transfer complex, while the radical cation salts are all semiconducting.

Magnetic molecular charge-transfer salts containing layers of water and tris(oxalato)ferrate(III) anions

We describe the synthesis, crystal structure and conducting properties of two new BEDT-TTF charge transfer salts of tris(oxalato)ferrate(III) containing slightly different numbers of water molecules, (BEDT-TTF)12[Fe(C2O4)3]2·xH2O [x = 15 (I) and 16 (II)]. I crystallizes in the monoclinic space groupC2/c, a = 36.017(10), b = 30.880(10), c = 36.183(15) A, α = 90, β = 93.66(3), γ = 90°, V = 40 161(23) A3, T = 120(2) K, Z = 8, R1 = 0.0842 [F2 > 2σ(F2)]; II crystallizes in the same space group, a = 17.9695(15), b = 15.4988(13), c = 36.115(3) A, α = 90, β = 93.720(2), γ = 90°, V = 10 037.1(14) A3, T = 150(2) K, Z = 4, R1 = 0.0673 [F2 > 2σ(F2)]. Electrical resistivity measurements show that I and II are semiconductors below 275 K.

Chirality in charge-transfer salts of BEDT-TTF of tris(oxalato)chromate(III)

Crystallisation from chiral electrolyte (R)-(−)-carvone has produced three new chiral semiconducting salts of BEDT-TTF from racemic anion tris(oxalato)chromate(III).

New molecular superconductor containing paramagnetic chromium(iii) ions

The molecular charge-transfer salt β″-(bedt-ttf) 4 [(H 2 O)Cr(C 2 O 4 ) 3 ]·PhCN [bedt-ttf = bis(ethylenedithio)tetrathiafulvalene], containing paramagnetic Cr III ions (S = 3/2), is a superconductor with T c = 6.0(5) K.

Polymorphism based on molecular stereoisomerism in tris(oxalato) Cr( III ) salts of bedt-ttf [bis(ethylenedithio)tetrathiafulvalene]

Polymorphs of the charge transfer salt (bedt-ttf)4[(H3O)- CrIII(C2O4)3]·PhCN [bedt-ttf = bis(ethylenedithio)tetrathiafulvalene] which are either superconducting or semiconducting differ in the spatial distribution of Δ and Λ enantiomers of [Cr(C2O4)3]3– within the unit cell.