The Ni(II) Complex of 2-Hydroxy-Pyridine-N-Oxide 2-Isothionate: Synthesis, Characterization, Biological Studies, and X-ray Crystal Structures Using (1) Cu Kα Data and (2) Synchrotron Data | Chapter 09 | New Advances in Materials Science and Engineering Vol. 2

C12H20N6NiO6S2 or NiL2(SCN)2](NH4)2.2H2O, where L is 2-hydroxy-pyridine-N-oxide, has been prepared and characterized using elemental analyses, IR, UV and visible spectrometry, magnetic moment measurements, thermal analyses and single crystal X-ray analyis. The results indicate that the complex reacts as a bidentate ligand and is bound to the metal ion via the two oxygen atoms of the ligand (HL). The activation energies, ∆E*, entropies ∆S*, enthalpies ∆H* and order of reactions have been derived from differential thermo-gravimetric (DTA) curves. Based on inhibition zone diameter measurements, the complex exhibited significant antibacterial activity against both Staphylococcus aureus and Escherichia coli. It also exhibited significant antifungal activity against Candida albicans, but no activity was found against Aspergillus flavus. The crystal structure of the Ni(II) complex [C12 H20 N6 Ni O6 S2], Mr = 467.17, was determined from Cu Kα X-ray diffraction data, λ = 1.54178 Å, at 100 K using direct methods. The crystals are monoclinic, space group P21/n with Z = 4 and a = 8.9893(2) Å, b = 17.6680(5) Å, c = 12.5665(3) Å, β = 108.609(1)°. In parallel with this study corresponding results were derived for the crystal structure determined independently from synchrotron X-ray diffraction data, λ = 0.61990 Å, at 100 K. The unit cell parameters derived in this experiment are a = 9.000(2) Å, b = 17.700(4) Å, c = 12.590(3) Å, β = 108.61(3)°. Both studies show 4 O and 2 N atoms coordinating Ni in a distorted octahedral arrangement. Each of the Ni 2-hydroxy-pyridinium-N-oxide moieties is highly planar and the S=C=N-Ni ligands are approximately linear. The crystal structure is characterised by a number of strong hydrogen bonds.

Author(s) Details

Mohamed A. Makhyoun
Department of Chemistry, Alexandria University, Alexandria, Egypt.

Rex A. Palmer
Department of Crystallography, Birkbeck College, London, UK.

Amina A. Soayed
Department of Chemistry, Alexandria University, Alexandria, Egypt.

Heba M. Refaat
Department of Chemistry, Alexandria University, Alexandria, Egypt.

Dina E. Basher
Department of Chemistry, Alexandria University, Alexandria, Egypt.

James Raftery
School of Chemistry, University of Manchester, Manchester, UK.

Carina M. C. Lobley
Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot Oxfordshire, OX11 0DE, UK.

Anna J. Warren
Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot Oxfordshire, OX11 0DE, UK.

Thomas Sorensen
Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot Oxfordshire, OX11 0DE, UK.

Mark Ladd
Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.

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