| Abstract
| - Self-assembly of binuclear copper(II) metallacyclophane complexes with two m-phenylene-substituted dioxamates as bridging ligands and coordinatively unsaturated mononuclear copper(II) or nickel(II) complexes with different polyamines as blocking ligands affords a new series of homo- and heterometallic, hexa- and pentanuclear complexes [(Cu2L2)(ML‘)x](2x-4)+ (M = Cu, x = 4; M = Ni, x = 3) possessing a unique ladderlike structure. The ferromagnetic coupling between the central CuII ions through the double m-phenylenediamidate-type bridge within the binuclear metallacyclophane core accounts for the high-spin ground state of the corresponding hexanuclear copper(II) (S = 1) and pentanuclear copper(II)−nickel(II) (S = 2) complexes.
- New homo- and heterometallic, hexa- and pentanuclear complexes of formula {[Cu2(mpba)2(H2O)F][Cu(Me5dien)]4}(PF6)3·5H2O (1), {[Cu2(Me3mpba)2(H2O)2][Cu(Me5dien)]4}(ClO4)4·12H2O (2), {[Cu2(ppba)2][Cu(Me5dien)]4}(ClO4)4 (3),and [Ni(cyclam)]{[Cu2(mpba)2][Ni(cyclam)]3}(ClO4)4·6H2O (4) [mpba = 1,3-phenylenebis(oxamate), Me3mpba =2,4,6-trimethyl-1,3-phenylenebis(oxamate), ppba = 1,4-phenylenebis(oxamate), Me5dien = N,N,N‘N‘ ‘,N‘ ‘-pentamethyldiethylenetriamine, and cyclam = 1,4,8,11-tetraazacyclotetradecane] have been synthesized through the useof the “complex-as-ligand/complex-as-metal” strategy. The structures of 1−3 consist of cationic CuII6 entities withan overall [2 × 2] ladder-type architecture which is made up of two oxamato-bridged CuII3 linear units connectedthrough two m- or p-phenylenediamidate bridges between the two central copper atoms to give a binuclearmetallacyclic core of the cyclophane-type. Complex 4 consists of cationic CuII2NiII3 entities with an incomplete [2 ×2] ladder-type architecture which is made up of oxamato-bridged CuIINiII and CuIINiII2 linear units connected throughtwo m-phenylenediamidate bridges between the two copper atoms to give a binuclear metallacyclophane core. Themagnetic properties of 1−3 and 4 have been interpreted according to their distinct “dimer-of-trimers” and “dimer-plus-trimer” structures, respectively, (H = −J(S1A·S3A + S1A·S4A + S2B·S5B + S2B·S6B) − J‘S1A·S2B). Complexes 1−4exhibit moderate to strong antiferromagnetic coupling through the oxamate bridges (−JCu-Cu = 81.3−105.9 cm-1;−JCu-Ni = 111.6 cm-1) in the trinuclear and/or binuclear units. Within the binuclear metallacyclophane core, aweak to moderate ferromagnetic coupling (J‘Cu-Cu = 1.7−9.0 cm-1) operates through the double m-phenylenediamidate bridge, while a strong antiferromagnetic coupling (J‘Cu-Cu = −120.6 cm-1) is mediated by thedouble p-phenylenediamidate bridge.
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