PREPARATION AND MOLECULAR-STRUCTURE OF THE TRANS(O-6) ISOMER OF DIHYDROGEN INE-N,N'-DIACETATO-N,N'-DI-3-PROPIONATO)COPPER(II) COMPLEX - THESTEREOCHEMISTRY OF COPPER(II)-EDTA-TYPE COMPLEXES IN RELATION TO THE STRUCTURE OF THE LIGAND

The hexadentate complex [Cu(H(2)1,3-pddadp)]. 1.5H(2)O (1,3-pddadp = p ropanediamine-N,N'-diacetate-N,N'-di-3-propionate ion) has been prepar ed and isolated and its molecular structure determined by the single c rystal X-ray diffraction technique. The complex is a trans(O-6) isomer , in which the copper(II) ion is surrounded octahedrally by two nitrog en and four oxygen atoms of 1,3-pddadp with two protonated beta-alanin ate rings in trans positions. The copper atom environment is a tetrago nally 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 chelat e rings only. Some properties of the complex are also given. Copyright (C) 1996 Elsevier Science Ltd