Synthesis, crystal structure and magnetic properties of a new dinuclear copper(II) amino acid complex [Cu2(l-arg)2(μ-HPO4-O)(μ-HPO4-O,O′)(μ-OH)]− · (H3O)+ · (H2O)6
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2007
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A novel dinuclear copper(II) complex with the amino acid l-arginine (l-arg), with mono and bidentate HPO42− oxoanions and an OH− anion. [Cu2(l-arg)2(μ-HPO4-O)(μ-HPO4-O,O′)(μ-OH)]− · (H3O)+ · 6H2O (1) was prepared and its structure was determined by X-ray diffraction methods. The two independent copper ions are in a distorted square pyramidal coordination, each bonded to one l-arginine molecule. These two Cu(l-arg) units are bridged by two monoatomic equatorial–apical oxygen ligands belonging to a monodentate hydrogenphosphate group, and to the hydroxyl group. The copper ions in the dinuclear unit at d = 3.1948(8) Å are also connected by two equatorial oxygen belonging to a bidentate hydrogenphosphate. This dinuclear character and bridging scheme, not common for metal–amino acid compounds, is a consequence of the properties of the phosphate anions. The magnetic susceptibility at temperatures between 2 and 300 K and the isothermal magnetization curves at T = 2.29(1) K with applied fields up to 9 T were measured. The magnetic data indicate an antiferromagnetic intradinuclear exchange coupling J/kB = −3.7(1) K and using a molecular field approximation we estimated a weaker ferromagnetic interaction J′/kB ∼ 0.3 K between neighbour dinuclear units.
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Copper, Arginine, Phosphate, Binuclear compound, Crystal structure, Magnetic properties
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SANTANA, Ricardo C. et al. Synthesis, crystal structure and magnetic properties of a new dinuclear copper(II) amino acid complex [Cu2(L-arg)2(mu-HPO4-O) (mu-HPO4-O,O')(mu-OH)]0.H3O+.(H2O)6. Polyhedron, Amsterdam, v. 26, p. 5001-5008, 2007. DOI:10.1016/j.poly.2007.07.005. Disponível em: https://www.sciencedirect.com/science/article/pii/S027753870700407X. Acesso em: 26 maio 2023.