A series of heterometal cyclic tetranuclear complexes [Cu IILMII(hfac)]2 (MII = Zn (1), Cu (2), Ni (3), Co (4), Fe(5), and Mn (6)) have been synthesized by the assembly reaction of K[CuL] and [MII(hfac)2(H2O) 2] with a 1:1 mole ratio in methanol, where H3L = 1-(2-hydroxybenzamido)-2-((2-hydroxy-3-methoxybenzylidene)amino)ethane and Hhfac = hexafluoroacetylacetone. The crystal structures of 2, 4, and [Cu IILMnII(acac)]2 (6a) (Hacac = acetylacetone) were determined by single-crystal X-ray analyses. Each complex has a cyclic tetranuclear CuII2MII2 structure, in which the CuII complex functions as a "bridging ligand complex", and the CuII and MII ions are alternately arrayed. One side of the planar CuII complex coordinates to one M" ion at the two phenoxo and the methoxy oxygen atoms, and the opposite side of the CuII complex coordinates to another M" ion at the amido oxygen atom. The temperature-dependent magnetic susceptibilities revealed spin states of SM = 0, 1/2, 1, 3/2, 2, and 5/2 for the Zn II, CuII, NiII, CoII, Fe II, and MnII ions, respectively. Satisfactory fittings to the observed magnetic susceptibility data were obtained by assuming a rectangular arrangement with two different g-factors for the CuII and MII ions, two different isotropic magnetic exchange interactions, J1 and J2, between the CuII and M II ions, and a zero-field splitting term for the MII ion. In all cases, the antiferromagnetic coupling constants were found for both exchange interactions suggesting nonzero spin ground states with ST = 2|SM - SCu|, which were confirmed by the analysis of the field-dependent magnetization measurements.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry