Syntheses and Crystal Structures of a Series of Manganese-Lanthanide-Sodium 12-Metallacrown-4 Dimers

Abstract

A series of heterotrimetallic manganese-lanthanide-sodium dimer metallacrowns has been synthesized and characterized by single-crystal X-ray analysis: {LnNa[12-MCMn(III)N(shi)-4]}2(iph)4, where LnIII = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Tm (12), Yb (13), Lu (14), and Y (15); MC is metallacrown; shi3− is salicylhydroximate; and iph2− is isophthalate. The manganese(III) ions and shi3− ligands generate the 12-MC-4 framework with one LnIII and Na+ ion bound to each [12-MCMn(III)N(shi)-4] on opposite sides of the central MC cavity. The carboxylate groups of the isophthalate ligands bridge between the central LnIII ion and each ring MnIII ion, and the meta-arrangement of the carboxylate groups joins two LnNa[12-MCMn(III)N(shi)-4] units together to form the dimer through the LnIII ions, which reside on the interior of the molecule. The identity of the central LnIII ion slightly impacts the size the [12-MCMn(III)N(shi)-4] framework. As the crystal radius of the LnIII ion increases from LuIII (1.02 A) to LaIII (1.19 A), the 12-MC-4 framework expands to accommodate the larger LnIII ion as the MC cavity increases in size (0.53 A for LuIII to 0.58 A for LaIII) and the average cross cavity MnIII-MnIII and oxime oxygen-oxime oxygen distances also increase (MnIII-MnIII distances: 6.48 A for LuIII to 6.52 A for LaIII; Ooxime-Ooxime distances: 3.66 A for LuIII to 3.75 A for LaIII). In addition, the larger LnIII ions reside further from the MC cavity as indicated by the LnIII-oxime oxygen mean plane (OoxMP) distance. The LnIII-OoxMP distance steadily decreases from LaIII (1.7527(12) A) to LuIII (1.5575(15) A). The complex {LaNa[12-MCMn(III)N(shi)-4]}2(iph)4(DMF)6(H2O)2 is a dimer of [12-MC-4] molecules linked by four isophthalate anions