New heterospin complexes have been obtained by combining the binu
clear complexes [{Cu(H
2O)L
1}Ln(O
2NO)
3] or[{CuL
2}Ln(O
2NO)
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 mononu
clear [CuL
1(2)] and the nickel dithiolene complexes [Ni(mnt)
2]
q- (
q= 1, 2; mnt = maleonitriledithiolate), as follows:
1![](/images/entities/infin.gif)
[{CuL
1}
2Ln(O
2NO){Ni(mnt)
2}]·Solv·CH
3CN (Ln = Gd
3+, Solv =CH
3OH (
1), Ln = Sm
3+, Solv = CH
3CN (
2)) and [{(CH
3OH)CuL
2}
2Sm(O
2NO)][Ni(mnt)
2] (
3) with [Ni(mnt)
2]
2-, [{(CH
3CN)CuL
1}
2Ln(H
2O)][Ni(mnt)
2]
3·2CH
3CN (Ln = Gd
3+ (
4), Sm
3+ (
5), Tb
3+ (
6)), and [{(CH
3OH)CuL
2}{CuL
2}Gd(O
2NO){Ni(mnt)
2}][Ni(mnt)
2]·CH
2Cl
2 (
7) with [Ni(mnt)
2]
-. Trinu
clear, 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 axialcoordination to the Cu centers, thus leading to the establishment of infinite chains.
3 is an ionic compound, containingdiscrete [{(CH
3OH)CuL
2}
2Sm(O
2NO)]
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 differenttypes of stacks, can be dis
closed. The strength of the intermolecular interactions between the open-shell species isestimated through extended Hückel calculations. In compound
7, [Ni(mnt)
2]
- radical anions coordinate group one of theCu centers of a trinu
clear [Cu
2Gd] motif through a CN, while discrete [Ni(mnt)
2]
- units are also present, overlapping inbetween, but also with the coordinated ones. Furthermore, the [Cu
2Gd] moieties dimerize each other upon linkage bytwo nitrato groups, both acting as chelate toward the gadolinium ion from one unit and monodentate toward a Cu ionfrom the other unit. The magnetic properties of the gadolinium-containing complexes have been determined. Ferromagneticexchange interactions within the trinu
clear [Cu
2Gd] motifs occur. In the compounds
4 and
7, the [Ni(mnt)
2]
- radicalanions contribution to the magnetization is
clearly observed in the high-temperature regime, and most of it vanishes upontemperature decrease, very likely because of the rather strong antiferromagnetic exchange interactions between theopen-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, wasestimated through CASSCF/CASPT2 calculations. Compound
6 exhibits a slow relaxation of the magnetization.