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

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 P1, 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.