Strong Ferromagnetic Exchange Coupling Mediated by a Bridging Tetrazine Radical in a Dinuclear Nickel Complex

The radical bridged compound [(Ni(TPMA))2-μ-bmtz•–](BF4)3·3CH3CN (bmtz = 3,6-bis(2′-pyrimidyl)-1,2,4,5-tetrazine, TPMA = tris(2-pyridylmethyl)amine) exhibits strong ferromagnetic exchange between the S = 1 NiII centers and the bridging S = 1/2 bmtz radical with J = 96 ± 5 cm–1 (−2JNi-radSNiSrad). DFT calculations support the existence of strong ferromagnetic exchange.