Strong Direct Magnetic Coupling in a Dinuclear Co^II Tetrazine Radical Single‐Molecule Magnet

Abstract

The ligand-centered radical complex [(CoTPMA)2 -μ-bmtz(.-) ](O3 SCF3 )3 ⋅CH3 CN (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 Co(II) 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 Co(II) ions.