Copper(II) perchlorate complexes with N-arylalkyliminodiacetamide ligands: X-ray structural, vibrational spectroscopic, DFT and thermogravimetric studies

The reactions of N-arylalkyl derivatives of iminodiacetamide (Bnimda, Peimda, Ppimda; Bn = benzyl, Pe = 2-phenylethyl; Pp = 3-phenylprop-1-yl) with copper(II) sulfate and sodium perchlorate in aqueous solutions were investigated. Three new copper(II) complexes [Cu(Bnimda)(2)](ClO4)(2) (1), [Cu(Peimda)(2)] (ClO4)(2) (2) and [Cu(Ppimda)(2)](ClO4)(2)center dot 2H(2)O (3) were prepared and characterized by infrared spectroscopy and thermal analysis (TG/DTA). Complex 2 was found to be explosive upon heating. The octahedral coordination environments around the copper(II) ions in complexes 1 and 3 consist of two O,N,O'-tridentate N-arylalkyliminodiacetamide ligands, with imino N atoms in trans-position. Molecules are interconnected by extensive hydrogen bonding between the amide moieties and perchlorate ions or water molecules, forming 3D networks in both structures. However, the difference in the hydrophobic chain lengths leads to significant differences in the hydrogen bonding motifs in the two structures. The molecular geometry and infrared spectra of these complexes were also studied by DFT calculations using B3LYP/6-311G(d,p) computational model. The calculated spectra and molecular geometry agree very well with the experimental results despite the extensive hydrogen bonding frameworks which are present in the crystal structures of these compounds. (C) 2017 Elsevier B.V. All rights reserved.