Dicobalt(II) complexes of a triazolate-containing Schiff-base macrocycle: synthesis, structure and magnetism

A new Schiff-base macrocycle is obtained by the lead(II) ion templated [2+2] condensation of 3,5-diacetyl-1H1,2,4-triazole and 1,4-diaminobutane in the presence of sodium hydroxide. Transmetallation of the resulting dilead complex, Pb2(L2)(ClO4)21, in acetonitrile with two equivalents of CoCl2·6H2O leads to the isolation of an orange, six-coordinate complex, [CoII2(L2)(OH2)3(NCCH3)](ClO4)2·H2O·2CH3CN 2. Subsequent reaction of 2 with two equivalents of NaOCN or NEt4Cl yielded red–purple five-coordinate [CoII2(L2)(NCO)2]3 and red fivecoordinate [CoII2(L2)(Cl)2]·1.5CH3CN 4, respectively. In all three air-stable dicobalt complexes the macrocycles contain two high-spin cobalt(II) centers which are weakly antiferromagnetically coupled (2J=–3.0, –0.4, –3.5 cm–1 for 2, 3 and 4, respectively). Complexes 2–4 have been characterized by X-ray diffraction and are the first structurally characterised complexes of a triazolate-containing macrocycle to date.