A new 3D MnII coordination polymer, [Mn2(HCO2)(L)2(N3)·MeOH]∞ (1) (L = nicotinate N-oxide), was synthesized by a solvothermal reaction and characterized magnetically. Complex 1 is a typical antiferromagnet with alternating azide/azide/formate/formate bridges, exhibiting a new –J1J1J2J2– coupling sequence. This is the first complex to contain an azide, formate and another type of carboxylate ligand.