Polar Ferromagnetic Metal by Intercalation of Metal–Amine Complexes

The metal–amine complex Co­(en)3, where en = ethylenediamine, intercalates between layers of cobalt sulfide (CoS) to form a polar, ferromagnetic metal. We solve the structure of the hybrid compound [Co­(en)3]­(CoS)12·en in the polar group Pca21 with lattice parameters a = 14.778(3) Å, b = 11.066(3) Å, and c = 20.095(5) Å using single-crystal X-ray diffraction. The [Co­(en)3]2+ complexes order between CoS layers and break their inherent fourfold symmetry. Moreover, the chiral Co­(en)3 complexes hydrogen bond to the terminal sulfides of the layers and break inversion symmetry, thereby inducing a polar state. The shortest hydrogen bond of the amino group is H···S = 2.41(1) Å. From 1.8 to 300 K, the title compound displays metallic electrical resistivity and an anomaly at 43 K. Through magnetization measurements, we find that Co­(en)3 exhibits spontaneous ferromagnetic order below 43 K. First-principles calculations reproduce the ferromagnetic structure and illustrate decoupling between the conducting electrons and the inversion-lifting distortion. Our work shows that hybrid materials created from intercalation chemistry of functional 2D hosts provides a pathway for uniting contraindicated properties.