Synthesis, characterization and crystal structures of two alkaline-earth metal complexes of olsalazine

Abstract

Two one-dimensional linear coordination polymers, [Mg(L) · 4(H2O)] (H2L = olsalazine) and 2 [Ca(L) · 4(H2O)] were obtained from self-assembly of CaCl2 or MgSO4 with olsalazine and their structures determined by single crystal X-ray diffraction. Both complexes are one-dimensional polymers, for complex 1 with crystal data: P2(1)/c, a = 9.5224(18), b = 11.309(2), c = 16.211(3) Å, β = 106.648(3)°, V = 1672.6(6) Å3, Z = 4, R 1 = 0.0695, wR 2 = 0.2183, for complex 2 with crystal data: P4(3)2(1)2, a = 10.4006(2), b = 10.4006(2), c = 32.0746(10) Å, V = 3469.59(14) Å3, Z = 8, R 1 = 0.0332, wR 2 = 0.1015. In the complexes, Mg and Ca adopt totally different coordination modes. Alkaline-earth Mg is six-coordinate octahedronal geometry, however, in 2, the local coordination geometry around calcium atom can be best described as a slightly distorted pentagonal bipyramid crystallizing in a homo-chiral space group. Olsalazine in both compounds also adopts dissimilar coordination modes.