Ligand Synthesis and Metal Complex Formation of 1,2,3-Triaminopropane

A series of linear primary polyamines H2N–CH2–(CH–NH2)n–CH2–NH2 (1 ≤ n ≤ 3) was prepared from the corresponding polyalcohols. The polyamines were isolated as HCl adducts and the acidity constants in aqueous solution were determined. The crystal structure of the fully protonated tetraamine (n = 2) was elucidated by an X-ray diffraction study. Complex formation of the triamine (n = 1) with Ni2+, Cu2+, Zn2+, Cd2+ was re-investigated in aqueous solution. The pH-dependent formation of a variety of species MxLyHz was established by potentiometric titrations and was compared with previous reports. The crystal structure of the Cu complex [CuL2]Cl2 exhibited a chain structure with a five-coordinate CuII centre in which two amino groups of the triamine ligands are coordinated to one Cu centre, while the third amino group of one of the ligands is bonded to a neighbouring Cu atom. The compound shows weak antiferromagnetic coupling interactions between the CuII centres within the chain.