Hydrogen-bonded copper(II) and nickel(II) complexes and coordination polymeric structures containing reduced Schiff base ligands

Complexes [Cu(HSas)(H2O)] center dot 2H(2)O (H(3)Sas = N-(2-hydroxybenzyl)-L-aspartic acid) (1), [Cu(HMeSglu) (H2O)] center dot 2H(2)O (H(3)MeSglu = (N-(2-hydroxy-5-methylbenzyl)-L-glutamic acid) (2), [Cu-2(Smet)(2)] (H(2)Smet = (N-(2-hydroxybenzyl)-L-methionine) (3), [Ni(HSas)(H2O)] (4), [Ni-2(Smet) (H2O)(2)] (5), and [Ni(HSapg)(2)] (H(2)Sapg = (N-(2-hydroxybenzyl)-L-aspargine) (6) have been synthesized and characterized by chemical and spectroscopic methods. Structural determination by single crystal X-ray diffraction studies revealed 1D coordination polymeric structures in 2 and 4, and hydrogen-bonded network structure in 5 and 6. In contrast to previously reported coordination compounds with similar ligands, the phenol remains protonated and bonded to the metal ions in 2 and 4, and also probably in 1. However, the phenolic group is non-bonded in 6. (C) 2009 Elsevier B.V. All rights reserved.