Strong Direct Magnetic Coupling in a Dinuclear CoII Tetrazine Radical Single‐Molecule Magnet

The ligand-centered radical complex [(CoTPMA)2-μ-bmtz.−](O3SCF3)3⋅CH3CN (bmtz=3,6-bis(2′-pyrimidyl)-1,2,4,5-tetrazine, TPMA=tris-(2-pyridylmethyl)amine) has been synthesized from the neutral bmtz precursor. Single-crystal X-ray diffraction studies have confirmed the presence of the ligand-centered radical. The CoII complex exhibits slow paramagnetic relaxation in an applied DC field with a barrier to spin reversal of 39 K. This behavior is a result of strong antiferromagnetic metal–radical coupling combined with positive axial and strong rhombic anisotropic contributions from the CoII ions.