Sodium and Magnesium Complexes with Dianionic α-Diimine Ligands

Abstract

A series of sodium and magnesium complexes with α-diimine ligands, [Na2(L iPr)(Et2O)]2 (1, L iPr = [(2,6- i Pr2C6H3)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 1−4, 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.

Mechanistic Insight into the NN Bond‐Cleavage of Azo‐Compounds that was Induced by an AlAl‐bonded Compound [L2−AlIIAlIIL2−]

“…The average C À N (1.359 ) and C À C bond lengths (1.401 ) of the C 2 N 2 moiety were consistent with the monoanionic radical form of the ligand. [22] [(L À ) 2 Al , but both distances were well within the currently known range for other related complexes. [24] In the Al 2 N 2 ring, the mean N-Al-N angle was 88.298 and the Al-N-Al angle was 91.718.…”

“…Synthesis: The AlÀAl-bonded complex [L 2À A C H T U N G T R E N N U N G (thf)Al II ÀAl II -A C H T U N G T R E N N U N G (thf)L 2À ] (1) was synthesized from the reduction of a mixture of [Na 2 L] (prepared in situ) [22] and AlCl 3 with 3 equivalents of sodium metal. The reaction of compound 1 with azobenzene, 4-methoxyazobenzene, and 4-dimethylaminoazobenzene gave imido compounds [L À Al III A C H T U N G T R E N N U N G (m 2 -NPh) 2 Al III L À ] (2), [L À Al III A C H T U N G T R E N N U N G (m 2 -NPh)(m 2 -NC 6 H 4 OMe)Al III L À ] (3), and [L À Al III -A C H T U N G T R E N N U N G (m 2 -NPh)(m 2 -NC 6 H 4 N(Me) 2 Al III L À ] (4), respectively.…”

The Manifold Structural Chemistry of Alkali Metal Enediamide Complexes

“…Table ). Coordinative saturation of the metal centers by intermolecular π‐aryl coordination has been reported for some solvent‐deficient sodium and potassium diazadienides , …”

Sodium and Potassium Salts of Mono‐ and Dianionic α‐Iminopyridines

“…Thus, in both cases, the a-diimine acts either as neutral ligand or as radical anion. Reduction of adiimines, using either alkali metals or electrochemical methods, leads in each case to the corresponding radical anions [15][16][17][18] and eventually to diamagnetic dianions, [17][18][19][20][21][22][23][24] albeit at much more negative potentials. In contrast to the well-established chemistry of a-diimines, the related a-iminopyridines are much less investigated.…”