Crystal structure of ca/^/ifl-hexakis(//-4-methylbenzoato)didysprosium(III), Dy2(C8H702)6

C48H42Dy20i2, triclinic, PI (no. 2), a = 8.155(2) A, b = 12.375(4) A , c = 22.168(6) A , a = 92.626(4)°, β = 95.868(4)°, γ = 90.261(4)°, V = 2223.0 A, Ζ = 2, R^F) = 0.033, wR^F) = 0.098, T= 293 K. Source of material 4-Methylbenzoic acid (1.5 mmol, 204 mg) was dissolved in ethanol (20 mL) and the pH of the solution was adjusted in the range 56 by using 2 Μ NaOH solution. The ethanol solution of DyCb 6H2O (0.5 mmol, 189 mg) was successively dropped in. The mixture was heated under reflux with stirring for 2 h and then kept in the flask for six days. Crystals of the title compound obtained were used for the X-ray diffraction analysis. Elemental analysis: found C, 51.00 %; H, 4.05 %; calc. for C48H42Dy20i2 C, 50.76 %; H, 3.73. Discussion Lanthanide carboxylate complexes display a variety of structural types, in which carboxylate groups link lanthanide ions in many coordination modes to form polynuclear compounds and one-, twoor three-dimensional coordination polymers. In the title complex, there exist two different coordination environments of Dy(m) ions. Dy 1 ion is coordinated by six Ο atoms (Ol, 03,09, Ol 1,06A and O8A) and Dy2 ion is surrounded by eight Ο atoms (02,04,05,06,07,09, OlO and 012A), both from six 4-methylbenzoato groups. Coordination number of lanthanide ions in most lanthanide carboxylate complexes is eight or nine, whereas the complexes with six ligands are rare. Dyl and Dy2 ions are connected to each other through two 4-methylbenzoato groups in bidentate bridging and one in tridentate bridging mode to form a dimeric subunit, [Dy(CH3C6H4COO)3]2These subunits are linked to form an infinite one-dimensional chain by bridging of 4-methylbenzoato groups. 01 -C1-02 and 03-C9-04 groups are in bidentate bridging, in which two Ο atoms coordinate two different Dy ions to form a bidentate bridge. 09-C33OlO groups are in bridging-chelating mode, in which two Ο atoms chelate one Dy ion and one of them also simultaneously links another Dy ion to form a tridentate bridge. The distances between two neighboring Dy ions are 4.121 A and 4.181 A, respectively, and the angle Dy2-Dyl-Dy2A is 158.4°. The crystal structure and coordination modes of carboxylate groups are different from those of Eu(p-CH3C6H4COO)3 [1] where carboxylate groups only adopt one bridging-chelating mode. The coordination environment of each Eu(m) ion is chemically equivalent, with eight coordinated Ο atoms, but unlike Nd(ffl) and Tb(m) [2] coordination polymers with 3-methylbenzoato. The structure of Nd(m-CH3C6H4COO)3 complex is similar to Eu(p-CH3C6H4COO)3. In Tb(p-CH3C6H4COO)3 complex, Tb ions are linked by two 3-methylbenzoato groups in chelating-bridging and one 3-methylbenzoato in bridging. It is obvious that the structural difference arises from different positions of the methyl group in the benzene ring. When a chelating ligand, 1,10-phenanthroline (phen) or 2,2'-bipyridine (bpy), was introduced to generate new mixed-ligand complexes, dinuclear molecules unlike the title complex were formed, such as Eu(pCH3C6H4COO)3(phen) [3] and Sm2(p-CH3C6H4COO)6(bpy)2 [4]. Dyl—Ο bond lengths range from 2.247(4) A to 2.307(4) A, with an average distance 2.278(4) A and Dy2—Ο bond lengths are in the range from 2.2593(5) A to 2.702(4) A, with an average distance of 2.394(4) A. The distances of Dyl—Ο are shorter than those of Dy2—O, which are attributable to different coordination environments of the two Dy(ÜI) ions. The 05-C17-06 and 09-C33-010 groups chelate Dy2 ions with two Ο atoms forming an unstable four-membered ring, resulting in longer Dy—Ο distances, <f(Dy2—O6) = 2.702(4) A and d(Dy2—09) = 2.652(4) A. * Correspondence author (e-mail: [email protected])