Structural and Magnetic Characterization of Two Tetranuclear Cu(II) Complexes with Closed‐Cubane‐Like Core Framework

Abstract

Two novel tetranuclear closed-cubane like core framework complexes [Cu4(L1)4]⋅3(H2O) (1) and [Cu4(H2L2)4(H2O)4] (2) (H2L1=(E)-2-((1-hydroxybutan-2-ylimino)methyl)phenol; H4L2=2-((2-hydroxy-3-methoxybenzylidene)amino)-2-hydroxymethylpropane-1,3-diol) were synthesized and structurally characterized. Magnetic susceptibility measurements indicate an overall weak antiferromagnetic exchange coupling in 1, while ferromagnetic exchange coupling in 2. In agreement with their closed-cubane structure, the magnetic behavior of the two complexes have been studied by employing the isotropic spin Hamiltonian of type H=J1 (S1S3 + S1S4 + S2S3 + S2S4) - J2 (S1S2 + S3S4) (J1 describes the magnetic exchange coupling between the four Cu(II) pairs with short Cu⋅⋅⋅Cu distances, while J2 characterizes the magnetic exchange coupling between the remaining two intermetallic pairs with long distances). The PHI program was used to study their magnetic behavior. A good agreement between the experimental and fitted curves was found with the following parameters: g=2.14, J1=-20.3 cm−1 and J2=0 cm−1 for 1 and g=2.10, J1=101.1 cm−1 and J2=-51.5 cm−1 for 2

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“…[12]. Next [13], and based on the Tercero et al [14] theoretical tasks, they determined the nature and magnitude of exchange couplings between Cu atoms of these complexes that are correlated with the Cu − O − Cu angle.…”

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