American Chemical Society
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Sodium and Magnesium Complexes with Dianionic α-Diimine Ligands

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posted on 2008-11-24, 00:00 authored by Yanyan Liu, Peiju Yang, Jie Yu, Xiao-Juan Yang, Jun D. Zhang, Zhongfang Chen, Henry F. Schaefer, Biao Wu
A series of sodium and magnesium complexes with α-diimine ligands, [Na2(LiPr)(Et2O)]2 (1, LiPr = [(2,6-iPr2C6H3)N(Me)C]2), [Na2(LMes)(solv)2]2 (LMes = [(2,4,6-Me3C6H3)N(Me)C]2, 2a, solv = Et2O; 2b, solv = THF), [Na4(LEt)2]n (3, LEt = [(2,6-Et2C6H3)N(Me)C]2), and [Mg(LMes)(THF)3] (4), have been synthesized by reduction of the diimine ligands with sodium or magnesium metal. Single-crystal X-ray diffraction analysis revealed that the sodium complexes have a 2:1 [Na2L] unit that aggregates to dimeric (1, 2a, 2b) or polymeric (3) structures, while the magnesium complex (4) shows a monomeric 1:1 structure. In all compounds 14, the ligand is doubly reduced to a dianion. The two Na+ ions in 1, 2a, 2b, and 3 show different coordination modes, one of which is chelated by the N donors of a ligand with supplementary Na−C bonds to the phenyl ring of another ligand within the [Na2L]2 dimer, while the other is bonded by the central C2N2 core of the ligand and solvent molecules (1, 2a, and 2b). Compound 3 displays a novel three-dimensional network. The Mg2+ ion in 4 is coordinated by a ligand molecule and three THF molecules. Density functional theory (DFT) computations on the sodium and magnesium complexes 1 and 4 confirmed their electronic structures and the dianionic character of the ligands.