Slow Magnetic Relaxation in Cobalt(II) Complexes with One-Dimensional Hydrogen-Bonded Networks

Two new cobalt(II) complexes with an unsymmetrical bidentate ligand, 2-(1,4,5,6-tetrahydropyrimidin-2-yl)-6-methoxyphenol (H2mthp), were synthesized and crystallographically characterized. Tetra- hexa-coordinate mononuclear selectively obtained by adjusting the stoichiometry of base. The coordination geometry hexa-coordinated complex was severely distorted from ideal octahedron, due to NO5 environment mixed one Hmthp− two H2mthp ligands. Both formed one-dimensional chain networks hydrogen-bond N-H···π interactions. Single-molecule magnet behavior observed for tetrahedral under zero magnetic field. relatively short Co···Co distances induced non-zero intermolecular coupling, which split ground ±Ms levels suppress quantum-tunneling magnetization. In octahedral complex, contrast, distance not enough induce coupling. As a consequence, single-molecule only in presence external static