catena-Poly[sodium-μ2-(N,N,N′,N′-tetra­methyl­ethane-1,2-diamine)-κ2N:N′-sodium-bis­[μ2-bis­(trimethyl­sil­yl)aza­nido-κ2N:N]]

Kennedy, A.R.; Mulvey, R.E.; O'Hara, C.T.; Robertson, S.D.; Robertson, G.M.

doi:10.1107/S1600536812045126

metal-organic compounds

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ISSN: 2056-9890

Volume 68| Part 12| December 2012| Page m1468

doi:10.1107/S1600536812045126

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catena-Poly[sodium-μ₂-(N,N,N′,N′-tetramethylethane-1,2-diamine)-κ²N:N′-sodium-bis[μ₂-bis(trimethylsilyl)azanido-κ²N:N]]

Alan R. Kennedy,^a Robert E. Mulvey,^a Charles T. O'Hara,^a Stuart D. Robertson ^a ^* and Gemma M. Robertson ^a

^aWestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, Scotland
^*Correspondence e-mail: stuart.d.robertson@strath.ac.uk

(Received 19 October 2012; accepted 31 October 2012; online 10 November 2012)

The title compound, [Na₂(C₆H₁₈NSi₂)₂(C₆H₁₆N₂)]_n, was found to consist of dimeric [Na(NSiMe₃)₂] units with crystallographically imposed centrosymmetry based upon four-membered NaNNaN rings. The dimers are bridged by N,N,N′,N′-tetramethylethylenediamine ligands, which act in an unusual extended non-chelating coordination mode. This gives a one-dimensional coordination polymer that extends parallel to the a-axis direction.

Related literature

For structures of non-solvated [Na(NSiMe₃)₂], see: Grüning & Atwood (1977 ); Driess et al. (1997 ); Knizek et al. (1997 ) and for THF-solvated [Na(NSiMe₃)₂], see: Sarazin et al. (2006 ); Karl et al. (1999 ). For similar complexes with diamine bridges between metal atoms, see: Henderson et al. (1997 ); Bernstein et al. (1992 ).

Experimental

Crystal data

[Na₂(C₆H₁₈NSi₂)₂(C₆H₁₆N₂)]
M_r = 482.98
Monoclinic, P 2₁ /n
a = 9.9761 (12) Å
b = 13.8292 (12) Å
c = 11.7983 (14) Å
β = 113.523 (14)°
V = 1492.4 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.24 mm⁻¹
T = 123 K
0.20 × 0.14 × 0.10 mm

Data collection

Oxford Diffraction Gemini S diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009 $[Oxford Diffraction (2010). CrysAlis PRO. Oxford Diffraction Ltd, Abingdon, England.]$ ) T_min = 0.942, T_max = 1.000
8332 measured reflections
3436 independent reflections
3064 reflections with I > 2σ(I)
R_int = 0.012

Refinement

R[F² > 2σ(F²)] = 0.023
wR(F²) = 0.067
S = 1.07
3436 reflections
135 parameters
H-atom parameters constrained
Δρ_max = 0.37 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: CrysAlis PRO (Oxford Diffraction, 2010) $[Oxford Diffraction (2010). CrysAlis PRO. Oxford Diffraction Ltd, Abingdon, England.]$ ; cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812045126/pk2451sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812045126/pk2451Isup2.hkl

checkCIF report

Comment top

Sodium 1,1,1,3,3,3-hexamethyldisilazide [Na(NSiMe₃)₂] is particularly useful in synthetic chemistry for the deprotonation reaction (the change of an inert C—H bond into a more useful C-metal bond) due to its low nucleophilicity and strong Brønsted basicity. The reactivity of this and similar organometallic reagents can generally be enhanced by the presence of a Lewis donor which operates by ligating the Lewis acidic metal centre and giving a lesser degree of oligomerization. One of the most common donors for this purpose is the diamine N,N,N',N'-tetramethylethylenediamine (TMEDA) which typically binds in a bidentate fashion. The unsolvated parent sodium amide is known to crystallize as either a one-dimensional chain polymer (Grüning & Atwood, 1977) or as a cyclotrimer (Knizek et al., 1997; Driess et al., 1997). Cyclodimeric Na(NSiMe₃)₂ ring forms with either one (Sarazin et al., 2006) or both Na centres solvated by tetrahydrofuran (Karl et al., 1999) are also known. We now report the structure of [Na(NSiMe₃)₂]₂.(TMEDA), (I), a Na₂N₂ cyclodimer with TMEDA binding to two sodium centres in a relatively unusual bridging rather than chelating fashion. A similar Li₂N₂ cyclodimer (N belonging to the related utility amide diisopropylamide, NⁱPr₂) bridged by TMEDA ligands (Bernstein et al., 1992) and a sodium hexamethyldisilazide cyclodimer bridged by the related ligand TMPDA, Me₂N(CH₂)₃NMe₂, (Henderson et al., 1997) have previously been reported.

(I) was prepared by mixing NaN(SiMe₃)₂ and TMEDA in a 2:1 ratio in hexane. The core structural motif is a crystallographically centrosymmetric four membered ring consisting of two Na centres and two N atoms from hexamethyldisilazide anions, with TMEDA binding to Na in a monodentate fashion, see Fig. 1. By acting as a bridging ligand to another Na₂N₂ ring, the TMEDA propagates the structure as a "polymer of dimers". This one dimensional polymer runs along the crystallographic a direction, see Fig. 2. The Na centres are three-coordinate and distorted trigonal planar. The Na—N_HMDS distances [2.436 (1) and 2.451 (1) Å] are consistent with those found in the related polymer of dimers with TMPDA acting as the bridging ligand (Henderson, et al. 1997), the Na—N_donor bond lengths are also comparable between these two structures.

Related literature top

For structures of non-solvated [Na(NSiMe₃)₂], see: Grüning & Atwood (1977); Driess et al. (1997); Knizek et al. (1997) and for THF-solvated [Na(NSiMe₃)₂], see: Sarazin et al. (2006); Karl et al. (1999). For similar complexes with diamine bridges between metal centres, see: Henderson et al. (1997); Bernstein et al. (1992).

Experimental top

All experimental manipulations were performed under an atmosphere of argon using either standard Schlenk techniques or a MBraun glove box fitted with an inert gas recirculation and purification system. NaHMDS was purchased from Aldrich and used as received. Hexane and toluene were distilled over sodium benzophenone prior to use. TMEDA was distilled over CaH₂ and stored over 4 Å molecular sieves prior to use. NMR spectroscopy data were recorded on a Bruker AV400 MHz spectrometer operating at 400.13 MHz for ¹H and 100.62 MHz for ¹³C. Na(NSiMe₃)₂ (0.73 g, 4 mmol) was suspended in dried hexane (10 ml) in an oven-dried Schlenk flask and this was sonicated for 10 min to give a white suspension. TMEDA (0.30 ml, 2 mmol) was introduced, followed by toluene (7.5 ml) to give a clear pale yellow solution. This was stirred for 3 h, heated and left in a freezer at 245 K. After 5 days only a small amount of crystalline material was observed. All solvents were removed under reduced pressure and toluene (8 ml) was added to give a clear yellow solution. This was heated and left to slowly cool, depositing a crop of colourless X-ray quality crystals in an 84% yield (0.81 g). ¹H NMR (400 MHz, C₆D₆, 300 K): δ 1.99 (s, 4H, TMEDA CH₂), 1.97 (s, 12H, TMEDA CH₃), 0.19 (s, 36H, SiMe₃). ¹³C NMR (100 MHz, C₆D₆, 300 K): δ 57.6 (TMEDA CH₂), 45.8 (TMEDA CH₃), 7.0 (SiMe₃).

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. View of the central dimeric unit of (I) showing 50% probability displacement ellipsoids.
	Fig. 2. Section of the one-dimensional polymeric coordination chain of (I) that extends along the crystallographic a direction.

catena-Poly[sodium-µ₂-(N,N,N',N'- tetramethylethane-1,2-diamine)-κ²N:N'-sodium- bis[µ₂-bis(trimethylsilyl)azanido-κ²N:N]] top

Crystal data top

[Na₂(C₆H₁₈NSi₂)₂(C₆H₁₆N₂)]	F(000) = 532
M_r = 482.98	D_x = 1.075 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 4914 reflections
a = 9.9761 (12) Å	θ = 2.9–29.1°
b = 13.8292 (12) Å	µ = 0.24 mm⁻¹
c = 11.7983 (14) Å	T = 123 K
β = 113.523 (14)°	Block, colourless
V = 1492.4 (3) Å³	0.20 × 0.14 × 0.10 mm
Z = 2

Data collection top

Oxford Diffraction Gemini S diffractometer	3436 independent reflections
Radiation source: fine-focus sealed tube	3064 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.012
ω scans	θ_max = 29.1°, θ_min = 3.0°
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	h = −13→13
T_min = 0.942, T_max = 1.000	k = −18→18
8332 measured reflections	l = −16→16

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.023	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.067	H-atom parameters constrained
S = 1.07	w = 1/[σ²(F_o²) + (0.0371P)² + 0.2964P] where P = (F_o² + 2F_c²)/3
3436 reflections	(Δ/σ)_max = 0.001
135 parameters	Δρ_max = 0.37 e Å⁻³
0 restraints	Δρ_min = −0.18 e Å⁻³

Crystal data top

[Na₂(C₆H₁₈NSi₂)₂(C₆H₁₆N₂)]	V = 1492.4 (3) Å³
M_r = 482.98	Z = 2
Monoclinic, P2₁/n	Mo Kα radiation
a = 9.9761 (12) Å	µ = 0.24 mm⁻¹
b = 13.8292 (12) Å	T = 123 K
c = 11.7983 (14) Å	0.20 × 0.14 × 0.10 mm
β = 113.523 (14)°

Data collection top

Oxford Diffraction Gemini S diffractometer	3436 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	3064 reflections with I > 2σ(I)
T_min = 0.942, T_max = 1.000	R_int = 0.012
8332 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.023	0 restraints
wR(F²) = 0.067	H-atom parameters constrained
S = 1.07	Δρ_max = 0.37 e Å⁻³
3436 reflections	Δρ_min = −0.18 e Å⁻³
135 parameters

Special details top

Experimental. Absorption correction: CrysAlisPro, Oxford Diffraction Ltd., Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Si1	0.92808 (3)	0.192359 (19)	0.06098 (2)	0.01444 (8)
Si2	1.02618 (3)	0.03467 (2)	0.26243 (2)	0.01598 (8)
Na1	1.16231 (4)	0.03368 (3)	0.03282 (4)	0.01891 (10)
N1	0.98789 (9)	0.08205 (6)	0.12110 (7)	0.01645 (17)
N2	1.42648 (9)	0.08786 (6)	0.08534 (8)	0.01989 (18)
C1	1.07176 (12)	0.26455 (8)	0.03194 (10)	0.0221 (2)
H1A	1.0329	0.3287	0.0005	0.033*
H1B	1.0986	0.2310	−0.0291	0.033*
H1C	1.1584	0.2715	0.1094	0.033*
C2	0.77062 (12)	0.17896 (8)	−0.09588 (10)	0.0215 (2)
H2A	0.7373	0.2431	−0.1311	0.032*
H2B	0.6899	0.1446	−0.0863	0.032*
H2C	0.8034	0.1423	−0.1512	0.032*
C3	0.86084 (12)	0.27808 (8)	0.15074 (10)	0.0220 (2)
H3A	0.8189	0.3356	0.1006	0.033*
H3B	0.9427	0.2973	0.2270	0.033*
H3C	0.7859	0.2460	0.1714	0.033*
C10	1.52737 (11)	0.01764 (8)	0.06673 (9)	0.0197 (2)
H10A	1.5393	−0.0385	0.1220	0.024*
H10B	1.6244	0.0482	0.0898	0.024*
C4	0.95775 (14)	0.10439 (9)	0.36540 (10)	0.0282 (3)
H4A	0.9842	0.0701	0.4440	0.042*
H4B	0.8512	0.1106	0.3250	0.042*
H4C	1.0022	0.1689	0.3809	0.042*
C5	1.22784 (12)	0.01762 (9)	0.35863 (10)	0.0263 (2)
H5A	1.2412	−0.0138	0.4368	0.039*
H5B	1.2765	0.0808	0.3756	0.039*
H5C	1.2704	−0.0229	0.3134	0.039*
C11	1.42724 (12)	0.17946 (8)	0.02160 (11)	0.0250 (2)
H11A	1.5278	0.2032	0.0488	0.038*
H11B	1.3678	0.2275	0.0416	0.038*
H11C	1.3866	0.1686	−0.0679	0.038*
C6	0.94484 (13)	−0.09035 (8)	0.24995 (10)	0.0252 (2)
H6A	0.9710	−0.1172	0.3329	0.038*
H6B	0.9832	−0.1323	0.2029	0.038*
H6C	0.8382	−0.0864	0.2075	0.038*
C12	1.47846 (13)	0.10829 (10)	0.21849 (11)	0.0311 (3)
H12A	1.5766	0.1366	0.2481	0.047*
H12B	1.4818	0.0480	0.2632	0.047*
H12C	1.4116	0.1538	0.2328	0.047*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Si1	0.01536 (13)	0.01393 (14)	0.01336 (13)	0.00077 (10)	0.00503 (10)	−0.00045 (9)
Si2	0.02043 (15)	0.01380 (14)	0.01380 (14)	0.00041 (10)	0.00692 (11)	−0.00009 (9)
Na1	0.0168 (2)	0.0193 (2)	0.0217 (2)	−0.00234 (15)	0.00880 (17)	−0.00370 (15)
N1	0.0199 (4)	0.0148 (4)	0.0154 (4)	0.0016 (3)	0.0078 (3)	−0.0005 (3)
N2	0.0187 (4)	0.0205 (4)	0.0230 (4)	−0.0024 (3)	0.0110 (4)	−0.0036 (3)
C1	0.0228 (5)	0.0213 (5)	0.0217 (5)	−0.0031 (4)	0.0086 (4)	0.0007 (4)
C2	0.0208 (5)	0.0218 (5)	0.0182 (5)	0.0010 (4)	0.0038 (4)	−0.0003 (4)
C3	0.0253 (5)	0.0198 (5)	0.0204 (5)	0.0056 (4)	0.0085 (4)	−0.0010 (4)
C10	0.0179 (5)	0.0209 (5)	0.0215 (5)	−0.0007 (4)	0.0091 (4)	−0.0007 (4)
C4	0.0445 (7)	0.0246 (6)	0.0213 (5)	0.0068 (5)	0.0191 (5)	0.0022 (4)
C5	0.0260 (6)	0.0242 (6)	0.0222 (5)	0.0017 (5)	0.0030 (4)	0.0006 (4)
C11	0.0230 (5)	0.0187 (5)	0.0355 (6)	−0.0030 (4)	0.0140 (5)	−0.0027 (4)
C6	0.0331 (6)	0.0193 (5)	0.0239 (5)	−0.0043 (4)	0.0121 (5)	0.0011 (4)
C12	0.0297 (6)	0.0400 (7)	0.0269 (6)	−0.0018 (5)	0.0148 (5)	−0.0086 (5)

Geometric parameters (Å, º) top

Si1—N1	1.6878 (9)	C1—H1C	0.9800
Si1—C3	1.8825 (11)	C2—H2A	0.9800
Si1—C1	1.8871 (11)	C2—H2B	0.9800
Si1—C2	1.8990 (11)	C2—H2C	0.9800
Si1—Na1	3.3176 (5)	C3—H3A	0.9800
Si1—Na1ⁱ	3.3185 (5)	C3—H3B	0.9800
Si2—N1	1.6874 (9)	C3—H3C	0.9800
Si2—C4	1.8798 (11)	C10—C10ⁱⁱ	1.526 (2)
Si2—C5	1.8890 (12)	C10—H10A	0.9900
Si2—C6	1.8904 (12)	C10—H10B	0.9900
Si2—Na1ⁱ	3.3667 (7)	C4—H4A	0.9800
Si2—Na1	3.4814 (6)	C4—H4B	0.9800
Na1—N1ⁱ	2.4356 (10)	C4—H4C	0.9800
Na1—N1	2.4509 (9)	C5—H5A	0.9800
Na1—N2	2.5665 (10)	C5—H5B	0.9800
Na1—C2ⁱ	3.0415 (12)	C5—H5C	0.9800
Na1—Na1ⁱ	3.1548 (9)	C11—H11A	0.9800
Na1—Si1ⁱ	3.3185 (6)	C11—H11B	0.9800
Na1—Si2ⁱ	3.3667 (7)	C11—H11C	0.9800
N1—Na1ⁱ	2.4356 (10)	C6—H6A	0.9800
N2—C12	1.4718 (14)	C6—H6B	0.9800
N2—C11	1.4748 (14)	C6—H6C	0.9800
N2—C10	1.4767 (13)	C12—H12A	0.9800
C1—H1A	0.9800	C12—H12B	0.9800
C1—H1B	0.9800	C12—H12C	0.9800

N1—Si1—C3	118.58 (5)	Si1—N1—Na1ⁱ	105.75 (4)
N1—Si1—C1	112.81 (5)	Si2—N1—Na1	113.26 (4)
C3—Si1—C1	103.65 (5)	Si1—N1—Na1	105.07 (4)
N1—Si1—C2	109.73 (5)	Na1ⁱ—N1—Na1	80.42 (3)
C3—Si1—C2	105.54 (5)	C12—N2—C11	107.94 (9)
C1—Si1—C2	105.51 (5)	C12—N2—C10	108.31 (8)
N1—Si1—Na1	45.51 (3)	C11—N2—C10	110.27 (8)
C3—Si1—Na1	153.67 (4)	C12—N2—Na1	101.78 (6)
C1—Si1—Na1	73.46 (4)	C11—N2—Na1	109.96 (6)
C2—Si1—Na1	100.34 (4)	C10—N2—Na1	117.86 (6)
C3—Si1—Na1ⁱ	132.10 (4)	Si1—C1—H1A	109.5
C1—Si1—Na1ⁱ	124.25 (4)	Si1—C1—H1B	109.5
C2—Si1—Na1ⁱ	64.79 (3)	H1A—C1—H1B	109.5
Na1—Si1—Na1ⁱ	56.771 (14)	Si1—C1—H1C	109.5
N1—Si2—C4	116.24 (5)	H1A—C1—H1C	109.5
N1—Si2—C5	114.14 (5)	H1B—C1—H1C	109.5
C4—Si2—C5	104.49 (6)	Si1—C2—H2A	109.5
N1—Si2—C6	110.93 (5)	Si1—C2—H2B	109.5
C4—Si2—C6	105.31 (5)	H2A—C2—H2B	109.5
C5—Si2—C6	104.70 (5)	Si1—C2—H2C	109.5
C4—Si2—Na1ⁱ	128.00 (4)	H2A—C2—H2C	109.5
C5—Si2—Na1ⁱ	127.42 (4)	H2B—C2—H2C	109.5
C6—Si2—Na1ⁱ	67.51 (4)	Si1—C3—H3A	109.5
C4—Si2—Na1	149.32 (4)	Si1—C3—H3B	109.5
C5—Si2—Na1	79.30 (4)	H3A—C3—H3B	109.5
C6—Si2—Na1	102.97 (4)	Si1—C3—H3C	109.5
Na1ⁱ—Si2—Na1	54.832 (15)	H3A—C3—H3C	109.5
N1ⁱ—Na1—N1	99.58 (3)	H3B—C3—H3C	109.5
N1ⁱ—Na1—N2	129.70 (3)	N2—C10—C10ⁱⁱ	112.28 (11)
N1—Na1—N2	130.73 (3)	N2—C10—H10A	109.1
N1ⁱ—Na1—C2ⁱ	63.70 (3)	C10ⁱⁱ—C10—H10A	109.1
N1—Na1—C2ⁱ	106.50 (3)	N2—C10—H10B	109.1
N2—Na1—C2ⁱ	96.82 (3)	C10ⁱⁱ—C10—H10B	109.1
N1ⁱ—Na1—Na1ⁱ	50.00 (2)	H10A—C10—H10B	107.9
N1—Na1—Na1ⁱ	49.58 (2)	Si2—C4—H4A	109.5
N2—Na1—Na1ⁱ	179.70 (3)	Si2—C4—H4B	109.5
C2ⁱ—Na1—Na1ⁱ	83.03 (3)	H4A—C4—H4B	109.5
N1ⁱ—Na1—Si1	105.13 (3)	Si2—C4—H4C	109.5
N1—Na1—Si1	29.42 (2)	H4A—C4—H4C	109.5
N2—Na1—Si1	118.63 (3)	H4B—C4—H4C	109.5
C2ⁱ—Na1—Si1	135.23 (3)	Si2—C5—H5A	109.5
Na1ⁱ—Na1—Si1	61.629 (15)	Si2—C5—H5B	109.5
N1ⁱ—Na1—Si1ⁱ	29.31 (2)	H5A—C5—H5B	109.5
N1—Na1—Si1ⁱ	104.73 (2)	Si2—C5—H5C	109.5
N2—Na1—Si1ⁱ	118.14 (2)	H5A—C5—H5C	109.5
C2ⁱ—Na1—Si1ⁱ	34.40 (2)	H5B—C5—H5C	109.5
Na1ⁱ—Na1—Si1ⁱ	61.599 (14)	N2—C11—H11A	109.5
Si1—Na1—Si1ⁱ	123.228 (14)	N2—C11—H11B	109.5
N1ⁱ—Na1—Si2ⁱ	28.45 (2)	H11A—C11—H11B	109.5
N1—Na1—Si2ⁱ	108.56 (3)	N2—C11—H11C	109.5
N2—Na1—Si2ⁱ	115.30 (3)	H11A—C11—H11C	109.5
C2ⁱ—Na1—Si2ⁱ	87.66 (2)	H11B—C11—H11C	109.5
Na1ⁱ—Na1—Si2ⁱ	64.434 (19)	Si2—C6—H6A	109.5
Si1—Na1—Si2ⁱ	99.467 (17)	Si2—C6—H6B	109.5
Si1ⁱ—Na1—Si2ⁱ	54.922 (9)	H6A—C6—H6B	109.5
N1ⁱ—Na1—Si2	105.53 (2)	Si2—C6—H6C	109.5
N1—Na1—Si2	26.44 (2)	H6A—C6—H6C	109.5
N2—Na1—Si2	119.53 (3)	H6B—C6—H6C	109.5
C2ⁱ—Na1—Si2	85.96 (2)	N2—C12—H12A	109.5
Na1ⁱ—Na1—Si2	60.735 (17)	N2—C12—H12B	109.5
Si1—Na1—Si2	53.868 (11)	H12A—C12—H12B	109.5
Si1ⁱ—Na1—Si2	97.166 (12)	N2—C12—H12C	109.5
Si2ⁱ—Na1—Si2	125.168 (15)	H12A—C12—H12C	109.5
Si2—N1—Si1	131.98 (5)	H12B—C12—H12C	109.5
Si2—N1—Na1ⁱ	108.11 (4)

N1—Si1—Na1—N1ⁱ	82.61 (5)	C6—Si2—Na1—Si2ⁱ	50.03 (4)
C3—Si1—Na1—N1ⁱ	144.37 (8)	Na1ⁱ—Si2—Na1—Si2ⁱ	0.0
C1—Si1—Na1—N1ⁱ	−128.21 (4)	C4—Si2—N1—Si1	14.19 (9)
C2—Si1—Na1—N1ⁱ	−24.95 (4)	C5—Si2—N1—Si1	−107.58 (8)
Na1ⁱ—Si1—Na1—N1ⁱ	25.47 (2)	C6—Si2—N1—Si1	134.44 (7)
C3—Si1—Na1—N1	61.76 (9)	Na1ⁱ—Si2—N1—Si1	132.73 (9)
C1—Si1—Na1—N1	149.18 (5)	Na1—Si2—N1—Si1	−140.13 (9)
C2—Si1—Na1—N1	−107.56 (5)	C4—Si2—N1—Na1ⁱ	−118.55 (6)
Na1ⁱ—Si1—Na1—N1	−57.14 (4)	C5—Si2—N1—Na1ⁱ	119.69 (5)
N1—Si1—Na1—N2	−123.05 (5)	C6—Si2—N1—Na1ⁱ	1.71 (6)
C3—Si1—Na1—N2	−61.29 (9)	Na1—Si2—N1—Na1ⁱ	87.14 (5)
C1—Si1—Na1—N2	26.13 (4)	C4—Si2—N1—Na1	154.32 (5)
C2—Si1—Na1—N2	129.40 (4)	C5—Si2—N1—Na1	32.55 (6)
Na1ⁱ—Si1—Na1—N2	179.82 (4)	C6—Si2—N1—Na1	−85.43 (6)
N1—Si1—Na1—C2ⁱ	14.89 (5)	Na1ⁱ—Si2—N1—Na1	−87.14 (5)
C3—Si1—Na1—C2ⁱ	76.65 (9)	C3—Si1—N1—Si2	−11.16 (9)
C1—Si1—Na1—C2ⁱ	164.07 (5)	C1—Si1—N1—Si2	110.22 (7)
C2—Si1—Na1—C2ⁱ	−92.66 (5)	C2—Si1—N1—Si2	−132.46 (7)
Na1ⁱ—Si1—Na1—C2ⁱ	−42.24 (3)	Na1—Si1—N1—Si2	142.42 (9)
N1—Si1—Na1—Na1ⁱ	57.14 (4)	Na1ⁱ—Si1—N1—Si2	−133.50 (9)
C3—Si1—Na1—Na1ⁱ	118.89 (8)	C3—Si1—N1—Na1ⁱ	122.33 (5)
C1—Si1—Na1—Na1ⁱ	−153.69 (4)	C1—Si1—N1—Na1ⁱ	−116.29 (5)
C2—Si1—Na1—Na1ⁱ	−50.42 (4)	C2—Si1—N1—Na1ⁱ	1.04 (5)
N1—Si1—Na1—Si1ⁱ	57.14 (4)	Na1—Si1—N1—Na1ⁱ	−84.09 (4)
C3—Si1—Na1—Si1ⁱ	118.89 (8)	C3—Si1—N1—Na1	−153.58 (4)
C1—Si1—Na1—Si1ⁱ	−153.69 (4)	C1—Si1—N1—Na1	−32.20 (6)
C2—Si1—Na1—Si1ⁱ	−50.42 (4)	C2—Si1—N1—Na1	85.13 (5)
Na1ⁱ—Si1—Na1—Si1ⁱ	0.0	Na1ⁱ—Si1—N1—Na1	84.09 (4)
N1—Si1—Na1—Si2ⁱ	111.17 (4)	N1ⁱ—Na1—N1—Si2	105.70 (5)
C3—Si1—Na1—Si2ⁱ	172.93 (8)	N2—Na1—N1—Si2	−74.29 (6)
C1—Si1—Na1—Si2ⁱ	−99.65 (4)	C2ⁱ—Na1—N1—Si2	40.45 (5)
C2—Si1—Na1—Si2ⁱ	3.61 (4)	Na1ⁱ—Na1—N1—Si2	105.70 (5)
Na1ⁱ—Si1—Na1—Si2ⁱ	54.035 (14)	Si1—Na1—N1—Si2	−150.43 (7)
N1—Si1—Na1—Si2	−15.79 (4)	Si1ⁱ—Na1—N1—Si2	76.17 (5)
C3—Si1—Na1—Si2	45.97 (8)	Si2ⁱ—Na1—N1—Si2	133.58 (4)
C1—Si1—Na1—Si2	133.39 (4)	N1ⁱ—Na1—N1—Si1	−103.87 (4)
C2—Si1—Na1—Si2	−123.35 (4)	N2—Na1—N1—Si1	76.14 (6)
Na1ⁱ—Si1—Na1—Si2	−72.925 (18)	C2ⁱ—Na1—N1—Si1	−169.12 (4)
N1—Si2—Na1—N1ⁱ	−80.15 (6)	Na1ⁱ—Na1—N1—Si1	−103.87 (4)
C4—Si2—Na1—N1ⁱ	−129.77 (9)	Si1ⁱ—Na1—N1—Si1	−133.41 (3)
C5—Si2—Na1—N1ⁱ	129.83 (4)	Si2ⁱ—Na1—N1—Si1	−75.99 (4)
C6—Si2—Na1—N1ⁱ	27.03 (5)	Si2—Na1—N1—Si1	150.43 (7)
Na1ⁱ—Si2—Na1—N1ⁱ	−23.00 (2)	N1ⁱ—Na1—N1—Na1ⁱ	0.0
C4—Si2—Na1—N1	−49.62 (9)	N2—Na1—N1—Na1ⁱ	−179.99 (4)
C5—Si2—Na1—N1	−150.02 (6)	C2ⁱ—Na1—N1—Na1ⁱ	−65.25 (3)
C6—Si2—Na1—N1	107.18 (6)	Si1—Na1—N1—Na1ⁱ	103.87 (4)
Na1ⁱ—Si2—Na1—N1	57.15 (5)	Si1ⁱ—Na1—N1—Na1ⁱ	−29.54 (2)
N1—Si2—Na1—N2	123.03 (6)	Si2ⁱ—Na1—N1—Na1ⁱ	27.88 (2)
C4—Si2—Na1—N2	73.41 (9)	Si2—Na1—N1—Na1ⁱ	−105.70 (5)
C5—Si2—Na1—N2	−26.99 (5)	N1ⁱ—Na1—N2—C12	−148.37 (7)
C6—Si2—Na1—N2	−129.79 (5)	N1—Na1—N2—C12	31.62 (9)
Na1ⁱ—Si2—Na1—N2	−179.82 (4)	C2ⁱ—Na1—N2—C12	−87.10 (7)
N1—Si2—Na1—C2ⁱ	−141.42 (5)	Si1—Na1—N2—C12	64.53 (7)
C4—Si2—Na1—C2ⁱ	168.96 (8)	Si1ⁱ—Na1—N2—C12	−115.64 (7)
C5—Si2—Na1—C2ⁱ	68.56 (4)	Si2ⁱ—Na1—N2—C12	−177.74 (6)
C6—Si2—Na1—C2ⁱ	−34.24 (4)	Si2—Na1—N2—C12	2.10 (8)
Na1ⁱ—Si2—Na1—C2ⁱ	−84.27 (3)	N1ⁱ—Na1—N2—C11	97.39 (7)
N1—Si2—Na1—Na1ⁱ	−57.15 (5)	N1—Na1—N2—C11	−82.62 (8)
C4—Si2—Na1—Na1ⁱ	−106.77 (8)	C2ⁱ—Na1—N2—C11	158.66 (7)
C5—Si2—Na1—Na1ⁱ	152.83 (4)	Si1—Na1—N2—C11	−49.71 (7)
C6—Si2—Na1—Na1ⁱ	50.03 (4)	Si1ⁱ—Na1—N2—C11	130.12 (6)
N1—Si2—Na1—Si1	17.47 (4)	Si2ⁱ—Na1—N2—C11	68.02 (7)
C4—Si2—Na1—Si1	−32.16 (8)	Si2—Na1—N2—C11	−112.14 (6)
C5—Si2—Na1—Si1	−132.56 (4)	N1ⁱ—Na1—N2—C10	−30.12 (9)
C6—Si2—Na1—Si1	124.65 (4)	N1—Na1—N2—C10	149.86 (7)
Na1ⁱ—Si2—Na1—Si1	74.616 (18)	C2ⁱ—Na1—N2—C10	31.14 (7)
N1—Si2—Na1—Si1ⁱ	−108.83 (5)	Si1—Na1—N2—C10	−177.22 (6)
C4—Si2—Na1—Si1ⁱ	−158.46 (8)	Si1ⁱ—Na1—N2—C10	2.61 (8)
C5—Si2—Na1—Si1ⁱ	101.14 (4)	Si2ⁱ—Na1—N2—C10	−59.49 (7)
C6—Si2—Na1—Si1ⁱ	−1.66 (4)	Si2—Na1—N2—C10	120.35 (6)
Na1ⁱ—Si2—Na1—Si1ⁱ	−51.686 (12)	C12—N2—C10—C10ⁱⁱ	173.03 (11)
N1—Si2—Na1—Si2ⁱ	−57.15 (5)	C11—N2—C10—C10ⁱⁱ	−69.05 (13)
C4—Si2—Na1—Si2ⁱ	−106.77 (8)	Na1—N2—C10—C10ⁱⁱ	58.31 (13)
C5—Si2—Na1—Si2ⁱ	152.83 (4)

Symmetry codes: (i) −x+2, −y, −z; (ii) −x+3, −y, −z.

Experimental details

Crystal data
Chemical formula	[Na₂(C₆H₁₈NSi₂)₂(C₆H₁₆N₂)]
M_r	482.98
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	123
a, b, c (Å)	9.9761 (12), 13.8292 (12), 11.7983 (14)
β (°)	113.523 (14)
V (Å³)	1492.4 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.24
Crystal size (mm)	0.20 × 0.14 × 0.10

Data collection
Diffractometer	Oxford Diffraction Gemini S diffractometer
Absorption correction	Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)
T_min, T_max	0.942, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	8332, 3436, 3064
R_int	0.012
(sin θ/λ)_max (Å⁻¹)	0.685

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.023, 0.067, 1.07
No. of reflections	3436
No. of parameters	135
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.37, −0.18

Computer programs: CrysAlis PRO (Oxford Diffraction, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 1999).

Acknowledgements

We gratefully acknowledge the UK Engineering and Physical Sciences Research Council (award No. EP/F063733/1 to REM) and for the award of a Career Acceleration Fellowship (award no EP/J001872/1) to CTOH, the Royal Society for a Wolfson research merit award to REM, the Royal Society of Edinburgh/BP Trust for the award of a Research fellowship to SDR and a University of Strathclyde RDF award to REM/SDR.

References

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