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

We report the first examples of radical-cation salts of BEDT-TTF with spiroborate anions [B(mandelate)2]− and [B(2-chloromandelate)2]−, synthesized from either enantiopure or racemic bidentate mandelate or chloromandelate ligands. In the salts prepared using enantiopure ligands only one of two diastereoisomers of the spiroborate anion is incorporated, with the boron centre having the same stereochemistry as the enantiopure ligand. For the racemic salts one racemic pair of spiroborate anions containing an R and an S mandelate ligand is incorporated. In certain solvents helical crystals were obtained when using spiroborate anions with enantiopure ligands. Electrical and magnetic properties, and band structure calculations are reported.