Reactions Between Dinuclear CuII–NiII Complexes and the Nitrito Ligand: A New One-Dimensional Complex [Cu(oxpn)Ni(µ-NO2)(trimen)]n(ClO4)n with Nitrite Acting as a Tridentate Bridging Ligand and Ferro- and Antiferromagnetic Alternation

The reaction of NiX2 · 6 H2O (X = NO3–, ClO4–), bidentate amine, [Cu(oxpn)] [oxpn = N,N′-bis(3-aminopropyl)oxamide] and sodium nitrite in ethanolic solution, leads to the formation of new Cu2+–Ni2+ complexes of general formula [Cu(oxpn)Ni(NO2)(aa)]n(X)n [1, X = ClO4–, aa = N,N,N′-trimethylethylenediamine (trimen); 2, X = ClO4–, aa = N,N,N′N′- tetramethylethylenediamine (tmen); 3, X = ClO4–, aa = N,N-dimethyl-N′-ethylethylenediamine (dmeten); 4, X = PF6–, aa = trimen; 5, X = PF6–, aa = dmeten]. The structure of complex 1 consists of [Cu(oxpn)Ni(trimen)]2+ units linked by a nitrite group acting as a tridentate ligand, giving a one-dimensional system separated by ClO4– anions. In contrast, the structure of complex 2 consists of isolated [Cu(oxpn)Ni(NO2)(tmen)]+ dinuclear units and uncoordinated ClO4– anions. The nitrite group acts as a bidentate ligand. Variable-temperature magnetic susceptibility studies were performed on 1–5. The J value through the oxamidato bridge is close to –110 cm–1 in all five cases. For complex 1, considered as a chain, a simulation of the χMT vs T was performed with the CLUMAG program. These calculations revealed the influence of the magnetic interactions between the dinuclear entities through the nitrito bridging ligand, on the susceptibility curves at low temperatures.