Nickel(II) complexes of tridentate anthracene based Schiff bases: syntheses, properties and crystal structures

Abstract

The crystal and molecular structures of Ni(II) complexes with two tridentate anthracene-containing Schiff bases are reported. The Schiff bases were prepared by condensation of 9-anthraldehyde with diethylenetriamine (adien) and with dipropylenetriamine (adipn). Complexes synthesized from Ni(O₂CCH₃)₂·4H₂O and the ligands (1 : 1 mol ratio) crystallize from methanol as [Ni(adien)(O₂CCH₃)₂(H₂O)] (1) and [Ni(adipn)(O₂CCH₃)₂]·2CH₃OH (2·2CH₃OH) in space groups P2₁/n and P2₁2₁2₁, respectively. In 1, the distorted octahedral N₃O₃ coordination sphere around the metal ion is formed by the meridional N₃-donor adien, two mutually trans unidentate acetates and one water molecule. The N₃O₃ coordination sphere constituted by the N₃-donor adipn, one unidentate acetate and one bidentate acetate in 2 can be best described as trigonal bipyramidal. The secondary amine-N of adipn, the O-atom of the unidentate acetate and the midpoint of the two O-atoms of the bidentate acetate occupy the three equatorial positions and two imine-N atoms of adipn lie in axial sites. In the crystal lattice, molecules of 1 exist as discrete dimers due to intermolecular hydrogen bonding and π–π interactions. In contrast, self-assembly of 2 via intermolecular π–π interactions leads to a one-dimensional supramolecular structure.

Keywords:

• Ni(II) complexes
• Anthracene
• Schiff bases
• Crystal structures
• Intermolecular interactions
• Self-assembly

Acknowledgements

Financial assistance for this work was provided by the Council of Scientific and Industrial Research (CSIR), New Delhi (Grant No. 01(1880)/03/EMR-II to S. Pal). We thank the University Grants Commission (UGC), New Delhi for the facilities provided under the Universities with Potential for Excellence program. X-ray crystallographic studies were performed at the National Single Crystal Diffractometer Facility, School of Chemistry, University of Hyderabad (funded by the Department of Science and Technology, New Delhi). Mr. V. K. Muppidi and Mr. C. P. Pradeep thank the CSIR and the UGC, respectively for research fellowships.

Notes

†Present address: Vice Chancellor, Goa University, Goa 403 206, India

Additional information

Notes on contributors

Panthapally S. Zacharias†

†Present address: Vice Chancellor, Goa University, Goa 403 206, India