Structures and Physical Properties of New β′-BEDT-TTF Tris-Oxalatometallate (III) Salts Containing Chlorobenzene and Halomethane Guest Molecules

We report the structures and physical properties of new β′-(BEDT-TTF)4[Fe(oxalate)3]·G salts where A = H3O+, G = PhCl; A = Rb+ G = Pyridine. The structure of the PhCl salt is isomorphous with β′-(BEDT-TTF)4[(H3O)M(oxalate)3] with other guest molecules. PhCl is ordered in die hexagonal pockets formed by the [(H3O)Fe(oxalate)3] layer. The electrical conductivity is metallic down to 100 K, below which the resistivity increases with decreasing temperature. The specific conductivity at room temperature is about 10 S/cm. We also report the salt β′-(BEDT-TTF)4[RbFe(oxalate)3]·Pyridine where Rb+ replaces H3O. The electrical resistivity shows metallic behavior down to 100 K. and turns up gradually to a maximum at 65 K below which the system re-enters the metallic state down to liquid helium temperature. Neither salt shows superconductivity down to 2 K. In addition, other new β′-(BEDT-TTF)4[(H3O)M(oxalate)3]·salts with M = Cr, Ga, Fe; G = CH2Cl2, CH2ClBr, CH2Br2 are also reported.