Magnetic, spectroscopic and X-ray crystallographic structural studies on copper(II) complexes of tridentate NNS Schiff base ligands formed from 2-acetylpyrazine and S-methyl- and S-benzyldithiocarbazates

Hamid, Malai Haniti S. A., Ali, Mhammad Akbar, Mirza, Aminul Huq, Bernhardt, Paul V., Moubaraki, Boujemaa and Murray, Keith S. (2009) Magnetic, spectroscopic and X-ray crystallographic structural studies on copper(II) complexes of tridentate NNS Schiff base ligands formed from 2-acetylpyrazine and S-methyl- and S-benzyldithiocarbazates. Inorganica Chimica Acta, 362 10: 3648-3656. doi:10.1016/j.ica.2009.04.019


Author Hamid, Malai Haniti S. A.
Ali, Mhammad Akbar
Mirza, Aminul Huq
Bernhardt, Paul V.
Moubaraki, Boujemaa
Murray, Keith S.
Title Magnetic, spectroscopic and X-ray crystallographic structural studies on copper(II) complexes of tridentate NNS Schiff base ligands formed from 2-acetylpyrazine and S-methyl- and S-benzyldithiocarbazates
Formatted title
Magnetic, spectroscopic and X-ray crystallographic structural studies on copper(II) complexes of tridentate NNS Schiff base ligands formed from 2-acetylpyrazine and S-methyl- and S-benzyldithiocarbazates
Journal name Inorganica Chimica Acta   Check publisher's open access policy
ISSN 0020-1693
Publication date 2009-04-23
Sub-type Article (original research)
DOI 10.1016/j.ica.2009.04.019
Open Access Status
Volume 362
Issue 10
Start page 3648
End page 3656
Total pages 9
Editor B Lippert
R J Puddephat
U Belluco
Place of publication Netherlands
Publisher Elsevier BV
Language eng
Subject C1
030207 Transition Metal Chemistry
970103 Expanding Knowledge in the Chemical Sciences
Abstract New copper(II) complexes of general empirical formula, [Cu(NNS)X] (NNS = anionic forms of the 2-acetylpyrazine Schiff bases of S-methyl- and S-benzyldithiocarbazate, Hapsme and Hapsbz) and X = Cl, Br, NCS and NO have been synthesized and characterized. X-ray crystal structures of the free ligand, Hapsbz and the complexes, [Cu(apsbz)(NO)], [Cu(apsme)(NCS)] and [Cu(apsme)Cl] have been determined. In the solid state, the Schiff base, Hapsbz remains in its thione tautomeric form with the thione sulfur atom trans to the azomethine nitrogen atom. X-ray diffraction shows that the [Cu(apsbz)(NO)] complex is a novel coordination polymer in which one of the nitrogen atoms of the pyrazine ring bridges two adjacent copper(II) ions. The Schiff base is coordinated to the copper(II) ion in its iminothiolate form via the thiolate sulfur atom, the azomethine nitrogen atom and one of the pyrazine nitrogen atoms, the overall geometry of each copper atom in the polymer being close to a square-pyramid. The complexes, [Cu(apsme)X] (X = NCS, Cl) are dimers in which each copper atom adopts a five-coordinate near square-pyramidal geometry with an NS coordination environment. The Schiff base coordinates as a uninegatively charged tridentate ligand chelating via the pyridine and azomethine nitrogen atoms and the thiolate sulfur atoms. A nitrogen atom of a unidentate thiocayanate or chloride ligand and a bridging sulfur atom from a second ligand completes the coordination sphere. Room temperature μ values for the complexes in the solid state are in the range 1.70-2.0 μ typical of uncoupled or weakly coupled Cu(II) centres. Variable temperature susceptibility studies show that the chain complex displays weak ferromagnetic coupling across the pyrazine bridges, while the S-bridged dinuclear compounds display either weak ferromagnetic or weak antiferromagnetic coupling that relates to subtle bridging geometry differences. EPR studies of frozen DMF solutions give rather similar g and A values for all compounds indicative of Cu (d) ground state orbitals on the Cu centers.
Keyword Acetylpyrazine Schiff bases
Copper(II) structures
Schiff bases derived from S-methyldithiocarbazate and S-benzyldithiocarbazate
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2010 Higher Education Research Data Collection
School of Chemistry and Molecular Biosciences
 
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Created: Thu, 03 Sep 2009, 17:50:59 EST by Mr Andrew Martlew on behalf of School of Chemistry & Molecular Biosciences