Heterospin systems constructed from [Cu2Ln]3+ and [Ni(mnt)2]1-,2- Tectons: First 3p-3d-4f complexes (mnt = maleonitriledithiolato)

New heterospin complexes have been obtained by combining the binuclear complexes {Cu(H(2)O)L(1)}Ln(O(2)NO)(3)] or {CuL(2)}Ln(O(2)NO)(3)] (L(1) = N,N'-propylene-di(3-methoxysalicylideneiminato); L(2) = N,N'-ethylene-di(3-methoxysalicylideneiminato); Ln = Gd(3+), Sm(3+), Tb(3+)), with the mononuclear CuL(1)(2)] and the nickel dithiolene complexes Ni(mnt)(2)](q)- (q = 1, 2; mnt = maleonitriledithiolate), as follows: (1)infinity{CuL(1)}(2)Ln(O(2)NO){Ni(mnt)(2)}].Solv.CH(3)CN (Ln = Gd(3+), Solv = CH(3)OH (1), Ln = Sm(3+), Solv = CH(3)CN (2)) and {(CH(3)OH)CuL(2)}(2)Sm(O(2)NO)]Ni(mnt)(2)] (3) with Ni(mnt)2]2-, {(CH(3)CN)CuL(1)}(2)Ln(H(2)O)]Ni(mnt)(2)]3.2CH(3)CN (Ln = Gd(3+) (4), Sm(3+) (5), Tb(3+) (6)), and {(CH(3)OH)CuL(2)}{CuL(2)}Gd(O(2)NO){Ni(mnt)(2)}]Ni(mnt)(2)].CH(2)Cl(2) (7) with Ni(mnt))(2]*-. Trinuclear, almost linear, CuLnCu] motifs are found in all the compounds. In the isostructural 1 and 2, two trans cyano groups from a Ni(mnt)2]2- unit bridge two trimetallic nodes through axial coordination to the Cu centers, thus leading to the establishment of infinite chains. 3 is an ionic compound, containing discrete {(CH(3)OH)CuL(2)}(2)Sm(O(2)NO)](2+) cations and Ni(mnt)(2)](2-) anions. Within the series 4-6, layers of discrete CuLnCu](3+) motifs alternate with stacks of interacting Ni(mnt)(2)](*-) radical anions, for which two overlap modes, providing two different types of stacks, can be disclosed. The strength of the intermolecular interactions between the open-shell species is estimated through extended Hückel calculations. In compound 7, Ni(mnt)(2)](*-) radical anions coordinate group one of the Cu centers of a trinuclear Cu(2)Gd] motif through a CN, while discrete Ni(mnt)(2)](*-) units are also present, overlapping in between, but also with the coordinated ones. Furthermore, the Cu(2)Gd] moieties dimerize each other upon linkage by two nitrato groups, both acting as chelate toward the gadolinium ion from one unit and monodentate toward a Cu ion from the other unit. The magnetic properties of the gadolinium-containing complexes have been determined. Ferromagnetic exchange interactions within the trinuclear Cu(2)Gd] motifs occur. In the compounds 4 and 7, the Ni(mnt)(2)](*-) radical anions contribution to the magnetization is clearly observed in the high-temperature regime, and most of it vanishes upon temperature decrease, very likely because of the rather strong antiferromagnetic exchange interactions between the open-shell species. The extent of the exchange interaction in the compound 7, which was found to be antiferromagnetic, between the coordinated Cu center and the corresponding Ni(mnt)(2)](*-) radical anion, bearing mostly a 3p spin type, was estimated through CASSCF/CASPT2 calculations. Compound 6 exhibits a slow relaxation of the magnetization.