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Synthesis of new pyrazole-containing binuclear and mononuclear Cu(II) complexes: crystal structure, EPR, magnetic and spectroscopic properties.

Autorzy

Barbara Barszcz

Tadeusz Głowiak

Julia Jezierska

Alina Tomkiewicz

Rok wydania

2004

Czasopismo

Polyhedron

Numer woluminu

23

Strony

1309-1316

DOI

10.1016/j.poly.2004.01.024

Kolekcja

Naukowa

Język

Angielski

Typ publikacji

Artykuł

Streszczenie

Reaction of 1-hydroxymethyl-3,5-dimethylpyrazole (LOH) with copper(II) salts yields new dinuclear [CuLLONO3]2 (1) or mononuclear CuL3(NO3)2 (2) co-ordination compounds, where L – (3,5-dimethylpyrazole), LO – (1-methoxy-3,5-dimethylpyrazole). The type of the obtained complex strongly depends on the solvent used during the preparation (propan-2-ol,T=298K for 1 and a mixture of solvents: methanol, propan-2-ol, trimethyl orthoformate, T=333K for 2). The crystal and molecular structure for both of the compounds were determined by single-crystal X-ray diffraction. The structure 1 consists of a dicopper complex with two bridging methoxide groups with a Cu–Cu separation of 2.958 (1) Å. Each copper atom is in a N2O3 donor set. The coordination geometry of the copper centres is described as distorted square-pyramidal with one of the oxygen atoms of the NO3− anion at the apex. The structure of 1 is compared with those observed previously for two similar [CuL(LO)X]2 complexes where X=BF4− (3) or ClO4− (4) instead of NO3− (1). Variable-temperature EPR spectra (77–295 K) and magnetic susceptibility measurements (1.9–300 K) indicate the antiferromagnetic exchange interaction is dependent on the compensating ligand; it is apparently smaller for the complex with X=NO3− than for those with X=BF4− and ClO4−, in agreement with the same order of increase of the Cu(II)–Cu(II) distances and bond angles of the bridging atoms. The structure of 2 is very close to regular square-pyramidal a with CuN3O2 chromophore formed by three L and one NO3− ligand, giving a trigonal distortion parameter (τ) of 0.094. The results of spectroscopic studies, IR, UV–Vis and EPR, of the compounds 1 and 2 appear to be in a good accord with the molecular structure determined by single-crystal X-ray analysis.Reaction of 1-hydroxymethyl-3,5-dimethylpyrazole (LOH) with copper(II) salts yields new dinuclear [CuLLONO3]2 (1) or mononuclear CuL3(NO3)2 (2) co-ordination compounds (L – 3,5-dimethylpyrazole; LO – 1-methoxy-3,5-dimethylpyrazole). The type of the obtained complex strongly depends on the solvent used during the preparation. The structural feature of (1) is compared with that observed previously for two similar [CuL(LO)X]2 complexes where X=BF4−(3) or ClO4− (4) instead of NO3− (1). Variable-temperature EPR spectra (77–295 K) and magnetic susceptibility measurements (1.9–300 K) indicate the antiferromagnetic exchange interaction dependent on the compensating ligand.

Słowa kluczowe

Dinuclear copper(II) complex, Magnetic properties, Bidentate ligand, Crystal structure, UV–Vis, EPR and IR spectra

Adres publiczny

https://doi.org/10.1016/j.poly.2004.01.024

Strona internetowa wydawcy

http://www.elsevier.com

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