A series of one-dimensional heterotrimetallic assemblies, [Cu2Ln(L)2(H2O)4][M(CN)6]·nH2O [Ln = Gd, M = Co (1), Fe (2), Cr (3), and Ln = La, M = Co (4), Fe (5), Cr (6)], were prepared by the reaction of a Cu2Ln precursor complex, [Cu2Ln(L)2(NO3)3], with K3[M(CN)6] in water. All of the assemblies were isomorphous and formed a 1D zigzag chain, in which the [Cu2Ln(L)2(H2O)4]3+ and [M(CN)6]3– units were alternately positioned and were linked in a Cu–NC–M–CN–Cu manner. Compound 1 showed magnetic behaviour similar to that of the discrete precursor complex, [Cu2Gd(L)2(NO3)3], owing to the diamagnetic nature of the [CoIII(CN)6]3– unit. In the case of 2, a simple summation of the magnetic behaviour of the [Cu2Gd(L)2(H2O)4]3+ and [Fe(CN)6]3– units was observed, whereas ferromagnetic interactions were found to be operative between the Cu2+ and Cr3+ ions in compound 3. The same magnetic interactions between Cu2+ and M3+ were confirmed in compounds 4 to 6, which included the diamagnetic La3+ ion. The differences in the magnetic behaviours of 2 and 3 can be explained by the overlap of the d(Cu)–pπ(CN) orbitals in the bent Cu–N≡C linkage and the spin-density on the cyanide nitrogen of the [Cr(CN)6]3– unit.
