Copper(II) complexes with new polypodal ligands presenting axial-equatorial phenoxo bridges {2-[(bis(2-pyridylmethyl)-amino)methyl]-4-methylphenol, 2-[(bis(2-pyridylmethyl)-amino)methyl]-4-methyl-6-(methylthio)phenol}: Examples of ferromagnetically coupled bi- and trinuclear copper(II) complexes

Jorge Manzur, Hector Mora, Andrés Vega, Evgenia Spodine, Diego Venegas-Yazigi, Maria Teresa Garland, M. Salah El Fallah, Albert Escuer

Resultado de la investigación: Contribución a una revistaArtículo

42 Citas (Scopus)

Resumen

Two new ligands, 2-[(bis(2-pyridylmethyl)amino)methyl]-4-methylphenol (HL) and 2-[(bis(2-pyridylmethyl)amino)methyl]-4-methyl-6-(methylthio)phenol (HSL), were synthesized and were used to prepare the trinuclear copper(II) complex {-[CuSL(Cl)]2·Cu}(PF6)2·H 2O (1) and the corresponding binuclear complexes [Cu 2(SL)2](PF6)2 (2) and [Cu 2L2](PF6)2 (3). The crystal structure of 1 shows two different coordination environments: two square base pyramidal centers (Cu1 and Cu1a, related by a C2 axes), acting as ligands of a distorted square planar copper center (Cu2) by means of the sulfur atom of the SCH3 substituent and the bridging phenoxo oxygen atom of the ligand (Cu2-S = 2.294 Å). Compounds 2 and 3 show two equivalent distorted square base pyramidal copper(II) centers, bridged in an axial-equatorial fashion by two phenoxo groups, thus defining an asymmetric Cu2O2 core. A long copper-sulfur distance measured in 2 (2.9261(18) Å) suggests a weak bonding interaction. This interaction induces a torsion angle between the methylthio group and the phenoxo plane resulting in a dihedral angle of 41.4(5)°. A still larger distortion is observed in 1 with a dihedral angle of 74.0(6)°. DFT calculations for 1 gave a ferromagnetic exchange between first neighbors interaction, the calculated J value for this interaction being +11.7 cm-1. In addition, an antiferromagnetic exchange for 1 was obtained for the second neighbor interaction with a J value of -0.05 cm-1. The Bleaney-Bowers equation was used to fit the experimental magnetic susceptibility data for 2 and 3; the best fit was obtained with J values of +3.4 and -16.7 cm-1, respectively. DFT calculations for 2 and 3 confirm the nature and the values of the J constants obtained by the fit of the experimental data. ESR and magnetic studies on the reported compounds show a weak exchange interaction between the copper(II) centers. The low values obtained for the coupling constants can be explained in terms of a poor overlap between the magnetic orbitals, due to the axial-equatorial phenoxo bridging mode observed in these complexes.

Idioma originalInglés
Páginas (desde-hasta)6924-6932
Número de páginas9
PublicaciónInorganic Chemistry
Volumen46
N.º17
DOI
EstadoPublicada - 20 ago 2007

Áreas temáticas de ASJC Scopus

  • Química física y teórica
  • Química inorgánica

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