Syntheses and Crystal Structures of Two Classes of Aluminum-Lanthanide-Sodium Heterotrimetallic 12-Metallacrown-4 Compounds: Individual Molecules and Dimers of Metallacrowns

Travis Jordan R.; Smihosky Alyssa M.; Kauffman Abigail C.Ramstrom Sven E.Lewis Alex J.Nagy Sarah G.Rheam Rachel E.Zeller MatthiasZaleski Curtis M.

摘要

Two series of aluminum-lanthanide-sodium 12-metallacrown-4 compounds have been synthesized and characterized by single-crystal X-ray analysis. For the individual LnNa(ben)(4)12-MCAl(III)N(shi)-4 molecules, where Ln(III) = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), Yb (8), Lu (9), and Y (10), ben(-)is benzoate, MC is metallacrown, and shi(3-)is salicylhydroximate, two independent molecules are present in each unit cell. The aluminum(III) ions and shi(3-)ligands comprise the MC framework, while the Ln(III)and Na(+)ions bind opposite of each other across the central MC cavity. The benzoate anions serve to tether the Ln(III)ion to the MC framework. When benzoate is replaced with the dicarboxylate anion isophthalate (iph(2-)), two 12-MCAl(III)N(shi)-4 units are connected to form a dimer of MCs: {LnNa12-MCAl(III)N(shi)-4}(2)(iph)(4), where Ln(III) = Eu (11), Gd (12), Tb (13), Dy (14), Ho (15), Ho (16), Er (17), Yb (18), and Lu (19). As in1-10, the aluminum(III) ions and shi(3-)ligands produce the MC frameworks, and one Ln(III)ion binds to each central MC cavity. However, there are two binding modes for the sodium ions. For12-15and18, the sodium ions bind to the central MC cavity opposite of the Ln(III)ions as in1-10. For11,16,17, and19, the sodium ions bind to the side of the MC framework by bonding to the phenolate and carboxylate oxygen atoms of two shi(3-)ligands and to the carboxylate oxygen atom of an iph(2-)ligand. In these structures, the MC cavity is vacant opposite of the Ln(III)ions. The substitution of isophthalate for benzoate does not significantly alter the 12-MCAl(III)N(shi)-4 framework as the size of the central MC cavity is not significantly different between analogous lanthanide individual and dimer MCs. However, the identity of the central Ln(III)ion does determine how close the Ln(III)ion can approach the mean plane of the oxime oxygen atoms (OoxMP) of the MC cavity. As the ion radius of the central Ln(III)ion decreases, the Ln(III)ion is able to more closely approach the OoxMP. For the individual MCs1-10, the Eu(III)of1is the farthest away from the OoxMP (1.55 angstrom) and this value steadily decreases to 1.44 angstrom for the Lu(III)ion of9. This same trend is true for the dimer MCs as the Eu(III)ion of11is 1.45 angstrom from the OoxMP and the Lu(III)ion of19is 1.36 angstrom from the OoxMP. Though the location of the sodium ions in the dimer MCs does influence the Ln(III)-OoxMP distance as the absence of the sodium ion in the MC cavity allows the Ln(III)ion to approach the MC cavity even closer. In15a sodium ion is opposite the Ho(III)ion and the Ho-III-OoxMP distance is 1.47 angstrom, while in16the sodium ion is bound to the side of the MC and the Ho-III-OoxMP distance is 1.40 angstrom. Graphic The complex GdNa12-MCAl(III)N(shi)-4}(2)(iph)(4)(DMF)(2)(H2O)(8)is a dimer of 12-MC-4 molecules linked by four isophthalate anions. GRAPHICS .

Syntheses and Crystal Structures of Two Classes of Aluminum-Lanthanide-Sodium Heterotrimetallic 12-Metallacrown-4 Compounds: Individual Molecules and Dimers of Metallacrowns

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