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Ci-Symmetry, [2 × 2] grid, square copper complex with the N4,N5-bis(4-fluorophenyl)-1H-imidazole-4,5-dicarboxamide ligand: structure, catecholase activity, magnetic properties and DFT calculations

Parween, Arfa; Naskar, Sumita; Mota, Antonio J.; Espinosa Ferao, Arturo; Chattopadhyay, Shyamal Kumar; Rivière, Eric; Lewis, William; Naskar, Subhendu

Authors

Arfa Parween

Sumita Naskar

Antonio J. Mota

Arturo Espinosa Ferao

Shyamal Kumar Chattopadhyay

Eric Rivière

William Lewis

Subhendu Naskar



Abstract

A new square tetranuclear copper complex of formula Cu4(LH)4·4DMF with the dinucleating amide ligand N4,N5-bis(4-fluorophenyl)-1H-imidazole-4,5-dicarboxamide (LH3) is reported herein. This ligand and the complex have been characterized by elemental analysis, FTIR, NMR, mass and UV-visible spectroscopy, as well as magnetic and electrochemical measurements. The single crystal X-ray diffraction study showed each Cu centre in a distorted square pyramidal environment, the square plane being formed by the extended coordination of two sets (N,N and N,O) of donor atoms from pairs of different ligands. The Cu4 unit has a Ci symmetry and crystallises in the P[1 with combining macron] space group in between DMF layers. The electronic spectrum of the complex exhibits a d–d transition at 676 nm. The complex also displays mild catecholase activity in DMF solution by using 3,5-di-tert-butylcatechol as substrate. Variable temperature magnetic measurements reveal an antiferromagnetic interaction between the copper centres with two different coupling constants of −143.4 and −169.0 cm−1. DFT calculations made on a single Cu4 unit from the crystal structure corroborated the antiferromagnetic coupling, the spin density of the lower-energy broken-symmetry state being consistent with an alternating +−+− singlet state operating at low temperature.

Journal Article Type Article
Publication Date Oct 21, 2017
Journal New Journal of Chemistry
Print ISSN 1144-0546
Electronic ISSN 1369-9261
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 41
Issue 20
APA6 Citation Parween, A., Naskar, S., Mota, A. J., Espinosa Ferao, A., Chattopadhyay, S. K., Rivière, E., …Naskar, S. (2017). Ci-Symmetry, [2 × 2] grid, square copper complex with the N4,N5-bis(4-fluorophenyl)-1H-imidazole-4,5-dicarboxamide ligand: structure, catecholase activity, magnetic properties and DFT calculations. New Journal of Chemistry, 41(20), https://doi.org/10.1039/C7NJ01667K
DOI https://doi.org/10.1039/C7NJ01667K
Publisher URL http://pubs.rsc.org/en/Content/ArticleLanding/2017/NJ/C7NJ01667K#!divAbstract
Copyright Statement Copyright information regarding this work can be found at the following address: http://eprints.nottingh.../end_user_agreement.pdf

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf





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