Preparation and molecular structure of the trans(O-6) isomer of dihydrogen (1,3-propanediamine-N,N-diacetato-N,N-di-3-propionato)copper(II) complex. The stereochemistry of copper(II)-EDTA-type complexes in relation to the structure of the ligand

Abstract

The hexadentate complex [Cu(H(2)1,3-pddadp)]. 1.5H(2)O (1,3-pddadp = 1,3-propanediamine-N,N-diacetate-N,N-di-3-propionate ion) has been prepared and isolated and its molecular structure determined by the single crystal X-ray diffraction technique. The complex is a trans(O-6) isomer, in which the copper(II) ion is surrounded octahedrally by two nitrogen and four oxygen atoms of 1,3-pddadp with two protonated beta-alaninate rings in trans positions. The copper atom environment is a tetragonally elongated octahedron with tetragonality (T) 0.798. A comparison of structures of the copper(II)-edta-type complexes shows an expected variation in their stereochemistry, depending on the structure of the ligand. The 1,3-pddadp ligand encircles the Cu-II ion more favourably than the edta ligand, which is capable of forming five-membered chelate rings only. Some properties of the complex are also given. Copyright (C) 1996 Elsevier Science Ltd