3 nm-wide Cyanometallate Fe-Co Tape Exhibiting Single-Chain Magnet Behavior

Abstract

Treatment of Co(OTf)₂·6H₂O, Li[(pzTp)Fe^III(CN)₃], and H₃PMo₁₂O₄₀·nH₂O in protic solvents afforded two structurally related Fe-Co cyanometallate complexes: [{(pzTp)Fe(CN)₃}₃Co₃(MeOH)₁₀][PMo₁₂O₄₀]·H₂O·11MeOH (1, pzTp^- = tetra(pyrazolyl)borate) and {[(pzTp)Fe(CN)₃]₄Co₃(MeOH)₅(H₂O)₃}_n[HPMo₁₂O₄₀]_n·3 nMeOH·6.5nH₂O (2). Complex 1 consists of a cyanide-bridged hexanuclear [Fe₃Co₃] cage, characterized by the fused conjunction of two mutually perpendicular trigonal bipyramids (TBPs, [Fe₂Co₃] and [Co₂Fe₃]), while complex 2 showcases an intricate cyanide-bridged Fe-Co tape comprising a central chain backbone of vertex-sharing [Fe₂Co₃] TBPs alongside peripheral [Fe₂Co₂] squares. Complex 2 is among the widest one-dimensional coordination assemblies characterized by the single-crystal X-ray diffraction technique. Magnetic studies revealed that complex 2 behaved as a single chain magnet with an effective energy barrier (U_eff/k_B) of 46.8 K. Our findings highlight the possibilities in the development of cyanometallate-POM hybrid materials with captivating magnetic properties.