Strong magnetic exchange coupling in a radical-bridged trinuclear nickel complex.

Reaction of 2,3,6,7,10,11-hexaaminotriphenylene hexahydrochloride (HATP·6HCl) and (Tp Ph Ni)Cl (Tp Ph = tris(3,5-diphenyl-1-pyrazolyl)borate) produces the radical-bridged trinickel complex [(Tp Ph Ni) 3 (HITP)] (HITP 3- ˙ = 2,3,6,7,10,11-hexaiminotriphenylene). Magnetic measurements and broken-symmetry density functional theory calculations reveal strong exchange coupling persisting at room temperature between HITP 3- ˙ and two of the three Ni 2+ centers, a rare example of strong radical-mediated magnetic coupling in multimetallic complexes. These results demonstrate the potential of radical-bearing tritopic HITP ligands as building blocks for extended molecule-based magnetic materials.