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(H2O)L-1}Ln(O2NO)(3)] or [{CuL2}Ln(O2NO)(3)] (L-1 = NAr-propylene-di(3-methoxysalicylideneiminato); L-2 = N,N'-ethylene-di(3-methoxysalicylideneiminato); Ln = Gd3+, SM3+, Tb3+), with the mononuclear [CuL1(2)] and the nickel dithiolene complexes [Ni(mnt)(2)](q-) (q = 1, 2; mnt = maleonitriledithiolate), as follows: (1)(infinity)[{CuL1}(2)Ln(O2NO){Ni(mnt)(2)}]center dot Solv center dot CH3CN (Ln = Gd3+, Solv = CH3OH (1), Ln = Sm3+, Solv = CH3CN (2)) and [{(CH3OH)CuL2}(2)Sm(O2NO)][Ni(mnt)(2)] (3) with [Ni(mnt)(2)](2-), [{(CH3-CN)CuL1}(2)Ln(H2O)][Ni(mnt)(2)](3)center dot 2CH(3)CN (Ln = Gd3+ (4), Sm3+ (5), Tb3+ (6)), and [{(CH3OH)CuL2}{CuL2}Gd(O2NO)-{Ni(mnt)(2)][Ni(mnt)(2)]center dot CH2Cl2 (7) with [Ni(mnt)(2)](center dot). 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 center dot) 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 [{(CH3OH)CuL2}(2)Sm(O2NO)](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)](center dot)- 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 Huckel calculations. In compound 7, [Ni(mnt)(2)](center dot)- radical anions coordinate group one of the Cu centers of a trinuclear [Cu2Gd] motif through a CN, while discrete [Ni(mnt)(2)](center dot)- units are also present, overlapping in between, but also with the coordinated ones. Furthermore, the [Cu2Gd] moieties climerize 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 [CU2Gd] motifs occur. In the compounds 4 and 7, the [Ni(mnt)2]center dot- 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)](center dot)- radical anion, bearing mostly a 3p spin type, was estimated through CASSCF/CASPT2 calculations. Compound 6 exhibits a slow relaxation of the magnetization.