Abstract

Three new complexes [Ni(β-dkt)<inf>2</inf>(NH<inf>2</inf>-quin) {β-dkt = 2,2,6,6-tetramethylheptane-3,3-dionate (tmhd) 1, hexafluoroacetylacetonate (hfac) 2, 1,3-diphenylpropanedionate (dbm) 3} have been prepared by reacting [Ni(β-dkt)<inf>2</inf>(H<inf>2</inf>O) <inf>2</inf> with 8-aminoquinoline (NH<inf>2</inf>-quin). [Ni(tmhd) <inf>2</inf>(NH<inf>2</inf>-quin) is found to be solvatochromic exhibiting a square planar geometry in CH<inf>2</inf>Cl<inf>2</inf>, acetone, and acetonitrile with the tmhd ligand acting unusually as a counteranion while in THF and DMSO the complex is octahedral. In contrast, 2 and 3 are octahedral in all solvents. Single crystal X-ray diffraction studies reveal octahedral nickel centres with a cis arrangement of the β-diketonates. The molecular packing consists of hydrogen bonded dimers which in the case of 2 and 3 are connected to one another via π⋯π and C-H⋯π interactions, respectively. Cyclic voltammetry shows 1 and 3 oxidise irreversibly at 0.46 and 1.17 V, respectively. © 2011 Elsevier Ltd. All rights reserved.