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

Abstract

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. 1. This paper describes the crystal structure of [Cu2(LCl)(μ-C6H5CO2)]·H2O as well as the synthesis and magnetic property.H3LCl was synthesized by a previously reported method. 6 To a methanol solution (10 cm 3 ) of H3LCl (28.4 mg, 0.0505 mmol) was added a methanol solution (8 cm 3 ) of copper(II) benzoate (31.3 mg, 0.102 mmol); the mixed solution was then stirred for 2018 A μ-phenolato-μ-benzoato-bridged dinuclear copper(II) complex with 2-(5-chloro-2-hydroxyphenyl)-1,3-bis(2-(5-chloro-2-hydroxybenzylideneamino)ethyl)imidazolidine (H3LCl) was synthesized. The crystal structure was determined by the single-crystal X-ray diffraction method at 90 K. The complex crystallizes as [Cu2(LCl)(μ-C6H5CO2)]·H2O in the monoclinic space group C2/c with a = 26.016 (7), b = 15.634(4), c = 18.360(5)Å, β = 109.073(3) , V = 7057(3)Å 3 , Dx = 1.553 g/cm 3 , Z = 8. The R1 [I > 2σ(I)] and wR2 (all data) values are 0.0543 and 0.1396, respectively, for all 8488 independent reflections. The two copper(II) atoms are bridged by the phenolato-oxygen of LCl 3and a monatomic-bridging benzoato ligand, where each copper(II) atom is further coordinated by a phenolato-oxygen, imino-and imidazolidine-nitrogen atoms of LCl 3in a meridional fashion to form a square-pyramidal geometry. The temperature dependence of the magnetic susceptibilities showed a ferromagnetic interaction with J = +22.8 cm -1 between the two copper(II) atoms.

Crystal Structure of a μ-Phenolato-μ-oxido-bridged Dinuclear Manganese(III) Complex with Dinucleating Schiff-base Ligand Having Three Phenolate Groups

“…[1][2][3][4][5][6][7] Previously, we reported unique dinuclear copper(II) complexes with a Schiffbase ligand having three phenolate donor atoms: 2-(5-chloro-2hydroxyphenyl)-1,3-bis(2-(5-chloro-2-hydroxybenzylideneamino)ethyl)imidazolidine (H3LCl), [Cu2(μ-LCl)(μ-CH3CO2)]•CH3CN• H2O and [Cu2(μ-LCl)(μ-C6H5CO2)]•H2O, where each copper atom is coordinated by phenolato-oxygen, imino-and imidazolidine-nitrogen atoms of LCl 3in a meridional fashion and the two copper atoms are bridged by the third phenolatooxygen of LCl 3and a μ-carboxylato group to form a squarepyramidal geometry. 8,9 As far as we know, there are no reports on a manganese complex with this type of Schiff-base ligands having three phenolate donor atoms. In this study, we isolated a new manganese complex by using an analogous Schiff-base ligand, 2-(5-nitro-2-hydroxyphenyl)-1,3-bis(2-(5-nitro-2-hydroxybenzylideneamino)ethyl)imidazolidine (H3LNO2), as single crystals, and determined the crystal structure, which shows a μ-phenolato-μ-oxido-bridged dinuclear manganese(III) complex with a distorted octahedral geometry, as shown in Fig.…”

“…2. In the dinuclear molecule, the two manganese atoms (Mn1 and Mn1′) are bridged by a phenolato-oxygen atom (O6) of LNO2 8,9 The elongated Mn1-N3 distance corresponds to the elongated Cu-N (imidazolidine) distances in the dinuclear copper(II) complexes, 8,9 and thus, the elongation may be due to the steric constraint imposed by the Schiff-base ligand. The elongation in the Mn1-O6 and Mn1-Cl1 bonds may reflect the pseudo Jahn-Teller distortion of the high-spin Mn(III) state.…”

“…The coordination mode is similar to the dinuclear copper(II) complexes with the analogous Schiff-base ligand; however, the oxidation state and the coordination geometry are different from the copper(II) cases. 8,9…”

Crystal Structure of a Mixed-valent Hexanuclear Manganese Complex Made-up from Two Oxido-centered Triangular Mn^IIMn^III₂ Cores

“…1 It is known that some Schiff-base ligands have an imidazoline ring as a consequence of a nucleophilic addition of a secondary amine. [1][2][3][4][5][6] The potentially heptadentate Schiff-base ligand was prepared by the condensation of triethylenetetramine with three equivalents of salicylaldehyde, as such an example. 2 Previously, we reported on the crystal structures of dinuclear manganese(III) complexes with a similar heptadentate Schiff-base ligand, 2-(5-nitro-2hydroxyphenyl)-1,3-bis(2-(5-nitro-2-hydroxybenzylideneamino)ethyl)imidazolidine (H3LNO2), having three phenolate donor atoms, where each metal atom is coordinated by phenolatooxygen, imino-and imidazolidine-nitrogen atoms of the Schiffbase ligand in a meridional (mer) fashion and the two metal atoms are bridged by a phenolato-oxygen atom of the pendent 5-nitro-salicylaldehyde group of LNO2 3-with an exogenous bridging group.…”

“…In this study, we performed a reaction of H3LNO2 with manganese acetate in the hope of obtaining a new complex with an acetato ligand as an exogenous bridging group for the two manganese atoms, because such a carboxylatobridge was found for the case of copper(II) complexes with an analogous Schiff-base ligand. 3,4 Intriguingly, we isolated a new hexanuclear manganese complex with the heptadentate Schiffbase ligand LNO2 3-and its hydrolyzed hexadentate Schiff-base ligand with an ethylenediamine backbone, LNO2′ 2-, by using a similar reaction of H3LNO2 with manganese(II) acetate tetrahydrate and determined the crystal structure of the isolated complex, [{Mn3(μ3-O)(μ-CH3COO)2(μ-LNO2)}2(LNO2′)]•2.5THF• CH3OH (Fig. 1).…”