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Large and negative magnetic anisotropy in pentacoordinate mononuclear Ni(ii) Schiff base complexes

Nemec, Ivan and Herchel, Radovan and Svoboda, Ingrid and Boča, Roman and Trávníček, Zdeněk (2015):
Large and negative magnetic anisotropy in pentacoordinate mononuclear Ni(ii) Schiff base complexes.
44, In: Dalton Trans., (20), pp. 9551-9560. Royal Society of Chemistry, ISSN 1477-9226,
[Article]

Abstract

A series of pentacoordinate Ni(II) complexes of the general formula [Ni(L5)] (1-6) with various pentadentate Schiff base ligands H(2)L5 (originating in a condensation of aromatic ortho-hydroxy-aldehydes and aliphatic triamines) was synthesized and characterized by X-ray structure analysis and magnetometry. The alternations of substituents on the H2L parent ligand resulted in the complexes with the geometry varying between the square-pyramid and trigonal-bipyramid. In the compounds whose chromophore geometry is closer to a trigonal-bipyramid, a large and negative uniaxial anisotropy (D = -64 cm(-1)) was identified. Moreover, the simple linear expression for the axial zero-field splitting (ZFS) parameter, D/cm(-1) = 32.7(4.8) - 151(10)tau, was proposed, where tau (in degrees) stands for the Addison parameter. The results of magnetic analysis were also supported by ab initio CASSCF/NEVPT2 calculations of the ZFS splitting parameters D and E, and g tensors. Despite large and negative D-values of the reported compounds, slow relaxation of magnetization was not observed either in zero or non-zero static magnetic field, thus no single-molecule magnetic behaviour was detected.

Item Type: Article
Erschienen: 2015
Creators: Nemec, Ivan and Herchel, Radovan and Svoboda, Ingrid and Boča, Roman and Trávníček, Zdeněk
Title: Large and negative magnetic anisotropy in pentacoordinate mononuclear Ni(ii) Schiff base complexes
Language: English
Abstract:

A series of pentacoordinate Ni(II) complexes of the general formula [Ni(L5)] (1-6) with various pentadentate Schiff base ligands H(2)L5 (originating in a condensation of aromatic ortho-hydroxy-aldehydes and aliphatic triamines) was synthesized and characterized by X-ray structure analysis and magnetometry. The alternations of substituents on the H2L parent ligand resulted in the complexes with the geometry varying between the square-pyramid and trigonal-bipyramid. In the compounds whose chromophore geometry is closer to a trigonal-bipyramid, a large and negative uniaxial anisotropy (D = -64 cm(-1)) was identified. Moreover, the simple linear expression for the axial zero-field splitting (ZFS) parameter, D/cm(-1) = 32.7(4.8) - 151(10)tau, was proposed, where tau (in degrees) stands for the Addison parameter. The results of magnetic analysis were also supported by ab initio CASSCF/NEVPT2 calculations of the ZFS splitting parameters D and E, and g tensors. Despite large and negative D-values of the reported compounds, slow relaxation of magnetization was not observed either in zero or non-zero static magnetic field, thus no single-molecule magnetic behaviour was detected.

Journal or Publication Title: Dalton Trans.
Volume: 44
Number: 20
Publisher: Royal Society of Chemistry
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Structure Research
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 21 Jan 2016 09:52
Official URL: http://dx.doi.org/10.1039/c5dt00600g
Identification Number: doi:10.1039/c5dt00600g
Funders: National Program of Sustainability I (LO1305) of the Ministry of Education, Youth and Sports of the Czech Republic, GACR 13-27355P, VEGA 1/0522/14, VEGA 1/0233/12, and APVV-0014-11 are acknowledged for the financial support.
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