Ferromagnetism in dinuclear copper(ii)-phenolate complexes with exogenous O-donor bridges: a comparative study

Abstract

The copper(II) complex Cu2L(OAc)(H2O)3.5, 1 x 3.5H2O was obtained and its reactivity in a basic medium investigated. Complex 1 x 3.5H2O shows different reaction patterns in air and in an inert atmosphere. Accordingly, interaction of 1 x 3.5H2O with Me4NOH x 5H2O in methanol-acetonitrile in air yields the hydroxide complex Cu2L(OH)(H2O)1.125, 2 x 1.125H2O while Cu2L(OMe)(MeOH)0.5(H2O), 3 x 0.5MeOH x H2O is isolated under an argon atmosphere. The products 1-3 were fully characterised and single crystals of {[Cu2L(OAc)] x MeCN x 3.5H2O}2, 1 x MeCN x 3.5H2O, {[Cu2L(OH)] x MeCN x 1.125H2O}2, 2 x MeCN x 1.125H2O and [Cu2L(OMe)] x 0.5MeOH x H2O, 3 x 0.5MeOH x H2O solved. The single X-ray study shows that 1-3 are dinuclear complexes with an endogenous phenol oxygen and an exogenous O-bridge. Magnetic characterisation of the three dinuclear complexes was performed, showing an apparent anomalous intramolecular ferromagnetic coupling between the metal atoms in all cases.

Di(2‐pyridyl) Ketone Complexes of CuI‐ and CuII‐Containing Iodide and Thiocyanate Ligands: An Unusual Case of a Mixed‐Aldol Condensation

“…[25] The magnetic moment increased to 1.96 μ B at 40 K. The μ eff vs. T (K) plot shows an increase in μ eff as the temperature is lowered, followed by a steep drop at low temperatures (40 K) which is characteristic of ferromagnetic coupling [34] and is confirmed by the positive J value of +45.2 cm -1 . The data for 3 is comparable to the magnetic data observed in other ferromagnetic alkoxo-bridged [29,30] and azido-bridged [28] complexes, with similar M-O-M angles and magnetic susceptibility plots, see Table 4.…”

“…Thus, the magnetic moment and magnetic susceptibility were measured for complex 3 and the results are presented in Figure 9. Although the more usual magnetic behaviour in Cu II d 9 dimeric species is a spin-pairing anti-ferromagnetic interaction (J -ve) as we have reported in previous studies, [27] a ferromagnetic interaction (J + ve) is not unique, [28][29][30] and complex 3 represents a further example. The data were fitted to the modified Bleaney-Bowers relationship [31] given in Equation (1) for a Cu II dimer, the spin Hamiltonian H = -2J S 1 S 2 where J is the exchange coupling parameter and S 1 = S 2 = 1/2 (interacting local spins).…”

μ-Phenolato-μ-acetato-bridged Dinuclear Copper(II) Complex with Dinucleating Schiff-base Ligand Having Three Phenolate Groups

“…The coordination geometries around the copper atoms and the molecular structure found in this study are similar to those of the dinuclear copper(II) complex with the bromo-derivative of the related Schiff-base ligands, although the crystal structure is different from the present one. 5 The diffused reflectance spectrum of the complex showed a CT band at 386 nm and a broad d-d band 718 nm with shoulder around 1000 nm. The d-d band feature is in agreement with the square-pyramidal geometry around the copper(II) ions.…”

“…1 So far, some dinuclear metal complexes with related Schiff-base ligands have been reported. [2][3][4][5] We have engaged in synthetic studies on dinuclear copper(II) complexes with Schiff-base ligands. [6][7][8] In this study, we isolated a dinuclear copper(II) complex with L 3-, and determined the crystal structure of this complex, which has not yet been reported, as shown in Fig.…”

μ-Phenolato-μ-benzoato-bridged Dinuclear Copper(II) Cluster with a Ferromagnetic Coupling

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51Schiff-bases, 2-(2-hydroxyphenyl)-1,3-bis(2-(2-hydroxy benzylideneamino)ethyl)imidazolidine (H3L) and its substituted derivatives are interesting dinucleating ligands, because they have three phenolate groups within the imdazolidine ligand, and afford dinuclear metal complexes with a cluster-like framework. [1][2][3][4][5][6][7] Recently, we reported on the crystal structure of a dinuclear copper(II) complex with the chloro-derivative of the Schiff-base ligands, 2-(5-chloro-2-hydroxyphenyl)-1,3-bis(2-(5-chloro-2hydroxybenzylideneamino)ethyl)imidazolidine (H3LCl). 6 In this study, we continued our study on these Schiff-base ligands, isolated a new dinuclear copper(II) complex with LCl 3-, and determined the crystal structure of the complex, which has a unique dinuclear structure, as shown in Fig.

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