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.

Graphical abstractThe reactions of N-aralkyl derivatives of iminodiacetic acid with nickel(II) salts were studied. Five new nickel(II) complexes were prepared and characterized by infrared spectroscopy and thermal analysis. The crystal structures of two complexes were determined by single-crystal X-ray structural analysis.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The reactions of N-aralkyliminodiacetic acids with nickel(II) salts were studied. ► Five new nickel(II) complexes were prepared. ► The complexes were characterized by spectroscopic and thermal measurements. ► The crystal structures were determined by single-crystal X-ray structural analysis.