Weak Ferromagnetic Ground State in Copper(II) Linear Chains

The linear chain Cu(II) compounds [{Cu(trpy)} 2 (μ-dicyd)] n [BPh 4 ] 2n , where trpy is 2,2′:6′,2″-terpyridine and dicyd 2− is 1,3-dicyanamidobenzene dianion, and [{Cu(trpy)(CF 3 SO 3 )}{Cu(trpy)}(μ-methyldicyd)] n [CF 3 SO 3 ] n , where methyldicyd 2− is 1,3-dicyanamido-2-methylbenzene dianion, both possess a weak ferromagnetic ground state despite having dramatically different bridging geometries. We suggest that the topology of the bridging ligand induces spin canting superimposed onto a dominant antiferromagnetic exchange interaction between the Cu(II) ions of the chain.