Syntheses and Crystal Structures of a Series of Dysprosium–Manganese–Sodium 12-Metallacrown-4 Compounds with Halogenated Benzoate Bridging Anions

Abstract

A series of heterotrimetallic dysprosium–manganese–sodium 12-metallacrown-4 compounds has been synthesized and characterized by single-crystal X-ray analysis: DyNaX4[12-MCMn(III)N(shi)-4], where X− = 2-fluorobenzoate (1), 3-fluorobenzoate (2), 4-fluorobenzoate (3), 2-chlorobenzoate (4), 4-chlorobenzoate (5), 3-bromobenzoate (6), and 2-iodobenzoate (7); MC is metallacrown; and shi3− is salicylhydroximate. Each 12-MC-4 framework is comprised of four ring MnIII ions and four shi3− ligands. The oxime oxygen atoms of the shi3− ligands produce a central cavity which then binds one DyIII ion and one Na+ ion on opposite sides. In each molecule four halogenated benzoate anions bridge between the central DyIII ion and the ring MnIII ions via the carboxylate groups. The identity of the halogenated benzoate anion has little effect on the structure of the [12-MCMn(III)N(shi)-4] framework as determined by several metrical parameters: the MC cavity radius, the average cross cavity MnIII–MnIII distance, the average cross cavity oxime oxygen-oxime oxygen distance, and the distance of the DyIII from the oxime oxygen mean plane. For 1–7 these metrical parameters are strikingly similar; thus, providing further reinforcement of one hallmark of metallacrown chemistry—the ability to substitute various components of the molecule without affecting the overall structure which can be used for the fine-tuning of molecular properties. Four 4-fluorobenzoate (4-Fben) anions bridge between the central DyIII ion and the ring MnIII ions in the metallacrown compound DyNa(4-Fben)4[12-MCMn(III)N(shi)-4](H2O)4·4DMF.