TRANS-N2S2-MACROCYCLIC LIGANDS WITH PENDANT CARBOXYLIC GROUPS - SYNTHESIS OF 6,7,8,9,15,16,17,18-OCTAHYDRODIBENZO[F,M][1,8,4,11]DITHIADIAZACYCLOTETRADECINE-8,17-DIACETIC ACID (H2L1) - STRUCTURES OF CORRESPONDING COPPER-COMPLEXES

The macrocyclic ligand with pendant carboxylic groups 6,7,8,9,15,16,17,18-octahydrodibenzo[f,m][1,8,4,11]dithiadiazacyclotetradecine-8,17-diacetic acid (H2L1) and its Ni(II) and Cu(II) complexes, [NiL1]3(H3O . ClO4)4 . H2O (1) and [Cu(HL1)]ClO4 . 1.5 H2O (2), have been prepared. The coordination properties of H2L1 towards Ni(II) and Cu(II) in aqueous solutions are independent on the pH according to UV/Vis-spectral measurements. The structures of 2 and of [CuL2]ClO4 (3) with HL2 = 6,7,8,9,15,16,17,18-octahydrodibenzo[f,m][1,8,4,11]dithiadiazacyclodetradecine-8-acetic acid have been determined by X-ray crystallography. In 2, all six donor atoms of the ligand are coordinated, forming an octahedron. Due to their size the metal atoms are not incorporated in the ligand cavity. The ligand is folded in such a way, that the N-donor atoms are in trans, and the S-(and O-)donor atoms in cis positions. In 3, the five donor atoms form a rather regular bipyramid with the N atoms in the axial positions. The stereochemistry of the ligands in the complexes 2 and 3 is discussed.