Progress in the thermodynamics of copper(II) polyamine complexes

The stability of transition metal complexes with aliphatic multidentate ligands is dependent on the size of the chelate rings. A variety of complexes contg. linked consecutive chelate rings are discussed in terms of stability related to the heat of formation. Cu(II) complexes of aliphatic tetraamines can coordinate a further anion to give 5-coordinate species. A study was made of the equils. of adduct formation in CH3OH soln. between square planar polyamine complexes and inorg. anions, according to the reaction. CuL2+ × X- .dblharw. CuLX+. The polyamines considered were: L = 2en, 2tn, (3,3,3-tet) and (2,3,2-tet), and X = iodide, thiocyanate and azide anions. N = trimethylethylene-diamine; 3,3,3-tet = N,N'-bis(3-aminopropyl)-1,3-propanediamine; and 2,3,2-tet = N,N'-bis(2-aminoethyl)-1,3-propanediamine.