Crystal Structure of μ-Oxido-μ-phenolato-bridged Dinuclear Manganese(III) Complex of Schiff-base Ligand with Bromido Coordination

Abstract

A dinuclear manganese(III) complex with 2-(5-nitro-2-hydroxyphenyl)-1,3-bis(2-(5-nitro-2-hydroxybenzylideneamino)ethyl)imidazolidine (H3LNO2) was synthesized. The crystal structure was determined by the single-crystal X-ray diffraction method at 90 K. The complex crystallized as [(C2H5)3NH][Mn2(μ-LNO2)(μ-O)Br2]•2THF in the orthorhombic space group Pnma with a = 14.890(2), b = 20.903(3), c = 14.7765( 19)Å, V = 4599.3(11)Å 3 , Dcalcd = 1.621 g/cm 3 , Z = 4. The R1 [I > 2σ(I)] and wR2 (all data) values are 0.0539 and 0.1260, respectively, for all 5416 independent reflections. The two manganese(III) atoms are bridged by a phenolato-oxygen atom of LNO2 3and a μ-oxido-oxygen atom, where each manganese(III) atom is further coordinated by phenolato-oxygen, imino-and imidazolidine-nitrogen atoms of LNO2 3in a meridional fashion and a bromido ligand to form a distorted octahedral geometry.

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

“…The charge balance and a bond valence sum calculation supported the mixed-valent Mn II 2Mn III 4 state. 12 In the crystal, there are intermolecular contacts between two nitro groups of the Schiff base LNO2 3and LNO2′ 2- 5,6 In the present complex, the two acetato ligands come from manganese(II) acetate work as a bridging group to form the μ3-oxido-centered triangular Mn II Mn III 2 core with the LNO2 3and LNO2′ 2ligands; the LNO2′ 2ligand works as a linker to form the hexanuclear Mn II 2Mn III 4 complex. The formation of the LNO2′ 2-ligand may be due to a hydrolysis reaction of the central imidazoline ring moiety of the LNO2 3-Schiff-base ligand during the reaction of the LNO2 3ligand with manganese(II) acetate tetrahydrate in the presence of a small amount of water coming from the metal source and/or the reaction solvents.…”

“…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.…”

“…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. 5,6 In these complexes, chlorido or bromido ligands bind to the manganese atom as the sixth site of the octahedral geometry. 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.…”

“…A Schiff-base ligand, H3LNO2, was synthesized by a method described in a previous paper. 5 [{Mn3(μ3-O)(μ-CH3COO)2(μ-LNO2)}2(LNO2′)]•2.5THF•CH3OH. To a tetrahydrofuran solution (20 cm 3 ) of H3LNO2 (61 mg, 0.10 mmol) was added a methanol solution (10 cm 3 ) of manganese(II) acetate tetrahydrare (50 mg, 0.20 mmol); ten drops of triethylamine were added to the mixed solution, and the reaction solution was heated with stirring for 15 min and then filtered.…”

Crystal Structure of a Hydrolyzed Product of the Cobalt(III) Complex with 1-(3,5-Dichlorosalicylideneamino)-3-amino-2-propanol

“…A similar hydrolysis reaction and the degradation of Schiff-base molecules were observed in a few of metal complexes with Schiff-base ligands. 10,17,18 Fig. 4 Diffused reflectance spectra of the title compound.…”