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-(met
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- 作者：Jorge Manzur ; Hector Mora ; André ; s Vega ; Evgenia Spodine ; Diego Venegas-Yazigi ; Marí ; a Teresa Garland ; M. Salah El Fallah ; Albert Escuer
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：August 20, 2007
- 年：2007
- 卷：46
- 期：17
- 页码：6924 - 6932
- 全文大小：221K
- 年卷期：v.46,no.17(August 20, 2007)
- ISSN：1520-510X
文摘
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)]2Cu}(PF6)2·H2O (1) and the corresponding binuclear complexes [Cu2(SL)2](PF6)2 (2) and [Cu2L2](PF6)2 (3).The crystal structure of 1 shows two different coordination environments: two square base pyramidal centers (Cu1 andCu1a, related by a C2 axes), acting as ligands of a distorted square planar copper center (Cu2) by means of the sulfuratom of the SCH3 substituent and the bridging phenoxo oxygen atom of the ligand (Cu2-S = 2.294 Å). Compounds 2and 3 show two equivalent distorted square base pyramidal copper(II) centers, bridged in an axial-equatorial fashion bytwo 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 thephenoxo plane resulting in a dihedral angle of 41.4(5)
s/entities/deg.gif">. A still larger distortion is observed in 1 with a dihedral angle of74.0(6)s/entities/deg.gif">. DFT calculations for 1 gave a ferromagnetic exchange between first neighbors interaction, the calculated Jvalue for this interaction being +11.7 cm-1. In addition, an antiferromagnetic exchange for 1 was obtained for the secondneighbor interaction with a J value of -0.05 cm-1. The Bleaney-Bowers equation was used to fit the experimentalmagnetic 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 experimentaldata. 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 themagnetic orbitals, due to the axial-equatorial phenoxo bridging mode observed in these complexes.