Hexabromorhenate(IV) salt of a trans-dioxorhenium(V) cation: X-ray structure and magnetic properties

A novel rhenium(IV)-rhenium(V) compound of formula NBu4[ReO2(py)4][ReBr6] (1) (NBu4 = tetra-n-butylammonium cation) was prepared, by reacting [ReBr6]2− and pyridine (py) in acetonitrile, and its crystal structure solved by X-ray diffraction. Compound 1 is the first reported salt of the trans-[ReO2(py)4)]+ cation in where a paramagnetic and highly anisotropic metal ion acts as anion.