Characterization of the Chloranilate(•3−) <i>π</i> Radical as a Strong Spin-Coupling Bridging Ligand

Dinuclear [(TPA)CoII(CA2-)CoII(TPA)](BF4)2·2MeOH (1) [TPA = tris(2-pyridylmethyl)amine] and [(TPA)CoII(CA•3-)CoII(TPA)](BF4)·2Et2O (2) with a bridging chloranilate radical ligand formed by reduction of 1 are crystallographically and magnetically characterized. 1 has shown a weak antiferromagnetic coupling within the CoII dimer [J/kB = −0.65 K (−0.45 cm-1)], while 2 has a 2 orders of magnitude stronger antiferromagnetic interaction between the CoII ion and a radical [J/kB = −75 K (52 cm-1)].