Ligand substitution reactions of the [ReX6]2− (X = Cl, Br) anions. Synthesis and crystal structure of novel oxalato complexes of rhenium(IV)

The reaction of K2[ReX6] (X = Cl, Br) with oxalic acid and triethylamine in dimethylformamide yields the complexes [ReX4(ox)]2− and cis-[ReX2(ox)2]2−, which can be obtained separately due to the kinetic inertness of Re(IV)-X bonds. The crystal structures of (PPh4)2[ReBr4(ox)], cis-(AsPh4)2[ReBr2(ox)2] and cis-(AsPh4)2[ReCl2(ox)2] have been determined by X-ray diffraction.