Unexpected magnetic topology in the heterobimetallic [ReIVBr4(μ-ox)CuII(bpy)2] compound

► [ReBr4(ox)]2− react with Cu2+ and bpy to give [ReIVBr4(μ-ox)CuII(bpy)2]. ► Intermolecular Br⋯Br and Cu⋯Br contacts lead to a 2-D supramolecular structure. ► [ReBr4(ox)Cu(bpy)2] behaves magnetically as a [ReIVCuII]2 tetranuclear species.