Ternary copper(II) complexes with 2,2′-bipyridine and N-tosyl-substituted amino acids. Part 2. Crystal and molecular structure of aqua(2,2′-bipyridine)bis(N-tosyl-DL-asparaginato-O)copper(II) dihydrate and (2,2′-bipyridine)(N-tosyl-DL-asparaginato-NO)copper(II) monohydrate

Abstract

The complexes [Cu(bipy)(tsasnO)₂(H₂O)]·2H₂O (1) and [Cu(bipy)(tsasnNO)]·H₂O (2) were separated from aqueous-alcoholic solutions at pH 4 and 6.4 respectively (tsasnO and tsasnNO =N-tosyl-DL-asparaginate monoanion and dianion respectively, bipy = 2,2′-bipyridine). The crystal and molecular structures were determined by X-ray diffraction. Compound (1) crystallizes in the space group P, with a= 18.162(4), b= 14.975(4), c= 7.272(2)Å, α= 103.67(6), β= 87.10(5), γ= 104.48(6)°, and Z= 2, while compound (2) crystallizes in the space group P2₁/c, with a= 12.421(9), b= 10.233(4), c= 17.773(7)Å, β= 101.65(2)° and Z= 4. In both compounds the copper atom exhibits a tetrahedrally distorted square-pyramidal geometry. In (1) the tsasnO monoanion acts as a monodentate carboxylate ligand leading to a CuN₂O₃ chromophore; in (2) the tsasnNO dianion acts as a tridentate ligand through the deprotonated sulphonamidic nitrogen, one carboxylic oxygen, and the amidic oxygen of the side chain, giving rise to a CuN₃O₂ chromophore.