Strong Direct Magnetic Coupling in a Dinuclear Co(II) Tetrazine Radical Single-Molecule Magnet.

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.

Crystal structure of di-µ-hydroxido-bis-[aqua-(1,10-phenanthroline-κ(2) N,N')copper(II)] naphthalene-2,6-di-carboxyl-ate hexa-hydrate.

In the title compound, [Cu2(OH)2(C12H8N2)2(H2O)2](C12H6O4)·6H2O, the two hydroxide groups bridge the two Cu(II) cations, forming a centrosymmetric binuclear complex cation, in which the Cu(II) cation is coordinated by a 1,10-phenanthroline (phen) mol-ecule, one water mol-ecule and two bridging hydroxide O atoms in a distorted N2O3 square-pyramidal coordination geometry. The naphthalene-2,6-di-carboxyl-ate anion is also located on an inversion centre. In the crystal, O-H⋯O hydrogen bonds link the cations, anions and lattice water mol-ecules into a three-dimensional supra-molecular architecture. Extensive π-π stacking is observed between the parallel or nearly parallel aromatic rings of adjacent phen ligands and naphthalenedi-carboxyl-ate anions, the centroid-to-centroid distances ranging from 3.4990 (16) to 3.8895 (16) Å.