Nickel(II) complexes with N-aralkyliminodiacetic acids: Preparation, spectroscopic, structural and thermal characterization

The reactions of N-aralkyl derivatives of iminodiacetic acid (H2Bnida, H2Peida, H2Ppida, o-H2Cbida, Bn = benzyl, Pe = 2-phenylethyl, Pp = 3-phenylprop-1-yl, o-Cb = o-chlorobenzyl) with nickel(II) chloride hexahydrate or nickel(II) acetate tetrahydrate in aqueous solutions were studied. Five new nickel(II) complexes [Ni(Bnida)(H2O)3]·H2O (1), [Ni(Peida)(H2O)3] (2), [Ni(Ppida)(H2O)3]·H2O (3a), [Ni(Ppida)(H2O)3] (3b) and [Ni(o-Cbida)(H2O)3] (4) were prepared and characterized by infrared spectroscopy and thermal analysis (TGA–DTA). The crystal structures of 1 and 3b were determined by single-crystal X-ray structural analysis. The octahedral coordination environment around the nickel(II) ion in 1 and 3b consists of an O,N,O′-tridentate N-aralkyliminodiacetate ion and three water molecules arranged in a fac-position. The molecules in the crystal structures of 1 and 3b are connected into a complicated hydrogen-bonded 2D network, dominated by the O–H⋯O hydrogen bonds. These 2D networks are in turn assembled into a 3D architecture only by weak van der Waals interactions.