Bis[μ-N-(tert-butyldimethylsilyl)quinolin-8-aminato-1:2κ2 N 1,N 8:N 8](N,N,N′,N′-tetramethylethane-1,2-diamine-1κ2 N,N′)lithiumsodium

In the heterometallic title bulky amido complex, [LiNa(C15H21N2Si)2(C6H16N2)], both alkali metal ions are four-coordinated with distorted tetrahedral geometries. The Li+ ion is N,N′-chelated by the N-silylated amido ligand, with Li—N = 2.015 (5) and 2.074 (5) Å. The two amido ligands are arranged cis to each other. The molecule exhibits a twofold rotational symmetry operation along the Li–Na axis. The Na+ ion is coordinated by two N atoms from the tetramethylethylenediamine ligand [Na—N = 2.553 (4) Å] and shares two amido N atoms from the N-silylated amido ligands with the Li+ ion. Although the crystal structure contains voids with an approximate volume of 50 Å3 there is no inclusion of solvent molecules.

In the heterometallic title bulky amido complex, [LiNa(C 15 H 21 N 2 Si) 2 (C 6 H 16 N 2 )], both alkali metal ions are four-coordinated with distorted tetrahedral geometries. The Li + ion is N,N 0 -chelated by the N-silylated amido ligand, with Li-N = 2.015 (5) and 2.074 (5) Å . The two amido ligands are arranged cis to each other. The molecule exhibits a twofold rotational symmetry operation along the Li-Na axis. The Na + ion is coordinated by two N atoms from the tetramethylethylenediamine ligand [Na-N = 2.553 (4) Å ] and shares two amido N atoms from the N-silylated amido ligands with the Li + ion. Although the crystal structure contains voids with an approximate volume of 50 Å 3 there is no inclusion of solvent molecules.
The research involving mixed organo-alkali metal amides is vivid as they could serve as superbase reagents and have interesting structures (Forbes et al., 2003;Mulvey, 2006;Wei et al., 2008). Based on the above work, we employed the bulky more demanding aminoquinoline analogue [HN(8-C 9 H 6 N)(SiBu t Me 2 )] to prepare a Li/Na hetero alkali metal amide. Its crystal structure is described here.
The title compound was prepared by metallation of the amine with half an equivalent of n-butyl lithium and half an equivalent of butyl sodium. Neutral donor TMEDA was added into the mixture and the red crystalline product was grown from hexane.
In the molecule of title compound, the lithium ion is fixed by two equivalents of the chelating quinolyl amido ligand, the corresponding bite angle N amido -Li-N quinolyl being 84.77 (12)°. The observed Li-N amido bond distance of 2.074 (5)Å is marginally different from reported values in literature and slightly longer than the Li-N quinolyl bond (2.015 (5)Å). It results a distorted tetrahedral configuration around the lithium ion. The sodium atom is connected by the amido nitrogen atoms and it is bound to the neutral donor TMEDA simultaneously, which also leads to a distorted tetrahedral geometry. The molecule exhibits a C 2 rotational symmetrical operation along the axis crossing Li and Na atoms. It makes the [Li-N amido -Na-N amido ] cyclic ring to be planar. The two metal atoms are separated by the distance of 2.951 (7)Å.

Experimental
A solution of 8-tert-butyldimethylsilylaminoquinoline (0.71 g, 2.73 mmol) in Et 2 O (ca 20 ml) was added into the mixture of n-LiBu (1.6 M, 0.86 ml, 1.37 mmol) and n-NaBu (0.11 g, 1.37 mmol) in Et 2 O (ca 20 ml) at 195 K. Then TMEDA (0.16 g, 1.37 mmol) was added and the resulting mixture was kept stirring overnight. The red solution was concentrated and the residue was recrystallized with hexane to give the title compound as red crystals (yield 0.35 g, 39%

Refinement
The methyl H atoms were constrained to an ideal geometry, with C-H distances of 0.96Å and U iso (H) = 1.5U eq (C), but each group was allowed to rotate freely about its C-C, C-N and C-Si bonds. The methylene H atoms were constrained with C-H distances of 0.97Å and U iso (H) = 1.2U eq (C). The quinolyl H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C-H distances in the range 0.93Å and U iso (H) = 1.2U eq (C).
The crystal structure contains four voids (V = 48Å 3 ) with coordinates: 0.000, 0.373, 0.250; 0.000, 0.627, 0.750; 0.500, 0.873, 0.250; 0.500, 0.127, 0.750. Inclusion of solvent molecules into the voids was not supported by diffraction experiment.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.011 Δρ max = 0.32 e Å −3 Δρ min = −0.26 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.