Complexation to Cadmium(II) of a Tetradentate Ligand Resulting from the Condensation of 2-Pyridinecarbaldehyde with <i>N</i>-(2-Aminoethyl)propane-1,3-diamine

The reaction of 2-pyridinecarbaldehyde with N-(2-aminoethyl)propane-1,3-diamine in a 2:1 molar ratio under microwave irradiation gave 2-(2-(pyridin-2-yl)-tetrahydropyrimidin-1(2H)-yl)-N-(pyridin-2-ylmethylene)ethanamine (L) as a mixture with the isomer 3-(2-(pyridin-2-yl)imidazolidin-1-yl)-N-(pyridin-2-ylmethylene)propan-1-amine (L^*). The molecules were characterized by elemental analyses and spectroscopic methods. Percentages of L and L^* were evaluated through integration of selected ¹H NMR signals. The cadmium iodide complex of L, [Cd(L)I₂]·H₂O (1), was prepared and identified by elemental analysis, FT-IR, Raman, and ¹H NMR spectroscopy, and single-crystal X-ray diffraction. In the crystal structure of 1 the cadmium atom with four coordinated nitrogen atoms and two iodide ions has a distorted octahedral geometry. A water molecule is also incorporated in the crystal network. Several hydrogen bonds including N–H···O, C–H···O, C–H···I, and O–H···I interactions are present in the crystal structure of 1.