Macrocycles based on magnetically functionalized zirconium oxide clusters

► Ni2+ and Co2+ complexes transform zirconium oxo-carboxylate clusters into isostructural 2.6 nm {M6Zr24} macrocycles. ► Intra-cluster condensation results in new {Zr12O22} framework. ► Some Ni2+/Co2+ sites display rare eightfold coordination. ► Antiferromagnetic coupling between spin centers is efficiently mediated by zirconium oxide fragments.