Effect of the β-diketonate ligand on the spin states of [Ni(β-dkt)2(NH2-quin)] complexes
作者:Darunee Sertphon、David J. Harding、Phimphaka Harding、Harry Adams
DOI:10.1016/j.poly.2011.08.014
日期:2011.10
Three new complexes [Ni(beta-dkt)(2)(NH2-quin)] beta-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(beta-dkt)(2)(H2O)(2)] with 8-aminoquinoline (NH2-quin). [Ni(tmhd)(2)(NH2-quin)] is found to be solvato-chromic exhibiting a square planar geometry in CH2Cl2, acetone, and acetonitrile with the tmhd ligand acting unusually as a counteranion while in THE 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 beta-diketonates. The molecular packing consists of hydrogen bonded dimers which in the case of 2 and 3 are connected to one another via pi...pi and C-H center dot center dot center dot pi interactions, respectively. Cyclic voltammetry shows 1 and 3 oxidise irreversibly at 0.46 and 1.17 V. respectively. (C) 2011 Elsevier Ltd. All rights reserved.