Crystal structures of two erbium(III) complexes with 4-aminobenzoic acid and 4-chloro-3-nitrobenzoic acid

Abstract

The crystal structures of two erbium(III) complexes with 4-aminobenzoic acid (4-ABAH), namely bis(μ2-4-aminobenzoato-κ2O:O′)bis[bis(4-aminobenzoato-κ2O,O′)diaquaerbium(III)] dihydrate, [Er2(C7H6NO2)6(H2O)4]·2H2O, (I), and 4-chloro-3-nitrobenzoic acid (CLNBAH), namely poly[hexakis(μ2-4-chloro-3-nitrobenzoato-κ2O:O′)bis(dimethyl sulfoxide-κO)dierbium(III)], [Er2(C7H3ClNO4)6(C2H6OS)2]n, (II), have been determined. In the structure of solvatomorphic compound (I), the symmetry-related irregular ErO8coordination polyhedra in the discrete centrosymmetric dinuclear complex comprise two monodentate water molecules and six carboxylate O-atom donors, four from two bidentate carboxylateO,O′-chelate groups and two from the bis-monodentateO:O′-bridging group of the third 4-ABA anion. The Er—O bond-length range is 2.232 (3)–2.478 (3) Å and the Er...Er separation in the dinuclear complex unit is 4.7527 (4) Å. One of the coordinating water molecules is involved in an intra-unit O—H...O hydrogen-bonding association with an inversion-related carboxylate O-atom acceptor. In contrast, the anhydrous compound (II) is polymeric, based on centrosymmetric dinuclear repeat units comprising ErO7coordination polyhedra which involve four O-atom donors from two bidentateO:O′-bridging carboxylate groups, one O-atom donor from the monodentate dimethyl sulfoxide ligand and two O-atom donors from the third bridging CLNBA anion. The latter provides the inter-unit link in the one-dimensional coordination polymer extending along [100]. The Er—O bond-length range in (II) is 2.239 (6)–2.348 (6) Å and the Er...Er separation within the dinuclear unit is 4.4620 (6) Å. In the crystal of (I), extensive inter-dimer O—H...O and N—H...O hydrogen-bonding interactions involving both the coordinating water molecules and the solvent water molecules, as well as the amine groups of the 4-ABA anions, give an overall three-dimensional network structure. Within this structure are also weak π–π ring interactions between two of the coordinating ligands [ring-centroid separations = 3.676 (3) and 3.711 (2) Å]. With (II), only weak intra-polymer C—H...O, C—H...Cl and C—H...S interactions are present.