Triangle, square and delta-chain based cobalt tetrazolate magnets

Abstract

Three novel tetrazole-based frustrated magnets, namely, Co₃(OH)₂(3-ptz)₂(SO₄)(H₂O)₄ (1), Co₂(OH)(tzba)(H₂O)₄ (2) and [Co(OH)(tta)] (3) (3-ptz = 5-(3-pyridyl) tetrazole, H₂tzba = 4-(1H-tetrazol-5-yl) benzoic acid, Htta = 1H-tetrazole) were hydrothermal synthesized and magnetically characterized. Compound 1 is a 2D (4,4) layered structure assembled by sulfate capped triangular [Co₃(μ₃-OH)(μ₃-SO₄)] clusters and in situ synthesized μ₃-3-ptz ligands. Compound 2 features Co₃(μ₃-OH) triangle based magnetic Δ-chains linked with in situ generated μ₅-tzba ligands to form a 2D layer. Compound 3 is a uninodal eight-connected body-centered-cubic (bcu) 3D network with square Co₄O₄ clusters as nodes and μ₄-tta ligands as linkers. Interestingly, spin frustration was observed in these complexes due to inherent spin competition in triangle, Δ-chain and square. Magnetic studies show that 1 behaves as antiferromagnet, while 2 and 3 exhibits spin canting and long-range magnetic ordering.