| Abstract |
The work in this paper reports syntheses, molecular and supramolecular structures, electrochemistry and magnetic properties of two diphenoxo-bridged dinickel(II) compounds [(Ni2L)-L-II(N-3)(2)(H2O)(2)]center dot CH3CN (1) and [(Ni2L)-L-II(N-3)(2)(H2O)] (2), where H2L is the tetraimino diphenolate macrocyclic ligand, obtained on [2 + 2] condensation of 4-methyl-2,6-diformylphenol and 2,2 -dimethyl-1,3-diaminopropane. Brown colored compound 1 and green colored compound 2 are produced from the same reaction mixture as a function of temperature; 1 is formed from the reaction mixture in acetonitrile at low temperature (ca. 5 degrees C), while 2 is formed on heating the reaction mixture in acetonitrile. Crystals of compounds 1 and 2 are monoclinic (space group P2(1)/c) and orthorhombic (space group P2(1)2(1)2(1)), respectively. Analyses of the crystal packing of the crystalline phases reveal that two-dimensional topologies are resulted in both 1 and 2 due to hydrogen bonding interactions. Variable-temperature (2-300 K) magnetic susceptibility measurements of the two compounds reveal that the metal centers in both the complexes are coupled by moderate anti-ferromagnetic interactions with J values (H = -2JS(1)center dot S-2) -18.8 and -34.2 cm(-1) for 1 and 2, respectively. Electrochemical analyses of 2 reveal that this compound exhibits two-step reduction couples at E-nu 2 = -977 and -1155 mV. (C) 2011 Elsevier Ltd. All rights reserved. |
