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 and Naskar, Sumita and Mota, Antonio J. and Espinosa Ferao, Arturo and Chattopadhyay, Shyamal Kumar and Rivière, Eric and Lewis, William and Naskar, Subhendu (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 . ISSN 1369-9261

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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.

Item Type: Article
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Chemistry
Identification Number: 10.1039/C7NJ01667K
Depositing User: Lewis, William
Date Deposited: 19 Sep 2017 13:05
Last Modified: 19 Oct 2017 16:05
URI: http://eprints.nottingham.ac.uk/id/eprint/46516

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