supplementary materials


pk2451 scheme

Acta Cryst. (2012). E68, m1468    [ doi:10.1107/S1600536812045126 ]

catena-Poly[sodium-[mu]2-(N,N,N',N'-tetramethylethane-1,2-diamine)-[kappa]2N:N'-sodium-bis[[mu]2-bis(trimethylsilyl)azanido-[kappa]2N:N]]

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

Abstract top

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.

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—NHMDS 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—Ndonor 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).

Refinement top

All H atoms were placed in idealized positions and refined in riding modes with C—H = 0.99 and 0.98 Å for CH2 and CH3 groups respectively and with Uiso(H) = 1.2 or 1.5 times Ueq(C) of the parent atom for CH2 and CH3 groups respectively. The orientation of the CH3 groups was refined by allowing rotation around the C—C and Si—C bonds.

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
[Figure 1] Fig. 1. View of the central dimeric unit of (I) showing 50% probability displacement ellipsoids.
[Figure 2] 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
Mr = 482.98Dx = 1.075 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 4914 reflections
a = 9.9761 (12) Åθ = 2.9–29.1°
b = 13.8292 (12) ŵ = 0.24 mm1
c = 11.7983 (14) ÅT = 123 K
β = 113.523 (14)°Block, colourless
V = 1492.4 (3) Å30.20 × 0.14 × 0.10 mm
Z = 2
Data collection top
Oxford Diffraction Gemini S
diffractometer
3436 independent reflections
Radiation source: fine-focus sealed tube3064 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.012
ω scansθmax = 29.1°, θmin = 3.0°
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2009)
h = 1313
Tmin = 0.942, Tmax = 1.000k = 1818
8332 measured reflectionsl = 1616
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.023Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.067H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.0371P)2 + 0.2964P]
where P = (Fo2 + 2Fc2)/3
3436 reflections(Δ/σ)max = 0.001
135 parametersΔρmax = 0.37 e Å3
0 restraintsΔρmin = 0.18 e Å3
Crystal data top
[Na2(C6H18NSi2)2(C6H16N2)]V = 1492.4 (3) Å3
Mr = 482.98Z = 2
Monoclinic, P21/nMo Kα radiation
a = 9.9761 (12) ŵ = 0.24 mm1
b = 13.8292 (12) ÅT = 123 K
c = 11.7983 (14) Å0.20 × 0.14 × 0.10 mm
β = 113.523 (14)°
Data collection top
Oxford Diffraction Gemini S
diffractometer
3064 reflections with I > 2σ(I)
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2009)
Rint = 0.012
Tmin = 0.942, Tmax = 1.000θmax = 29.1°
8332 measured reflectionsStandard reflections: 0
3436 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.023H-atom parameters constrained
wR(F2) = 0.067Δρmax = 0.37 e Å3
S = 1.07Δρmin = 0.18 e Å3
3436 reflectionsAbsolute structure: ?
135 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
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
xyzUiso*/Ueq
Si10.92808 (3)0.192359 (19)0.06098 (2)0.01444 (8)
Si21.02618 (3)0.03467 (2)0.26243 (2)0.01598 (8)
Na11.16231 (4)0.03368 (3)0.03282 (4)0.01891 (10)
N10.98789 (9)0.08205 (6)0.12110 (7)0.01645 (17)
N21.42648 (9)0.08786 (6)0.08534 (8)0.01989 (18)
C11.07176 (12)0.26455 (8)0.03194 (10)0.0221 (2)
H1A1.03290.32870.00050.033*
H1B1.09860.23100.02910.033*
H1C1.15840.27150.10940.033*
C20.77062 (12)0.17896 (8)0.09588 (10)0.0215 (2)
H2A0.73730.24310.13110.032*
H2B0.68990.14460.08630.032*
H2C0.80340.14230.15120.032*
C30.86084 (12)0.27808 (8)0.15074 (10)0.0220 (2)
H3A0.81890.33560.10060.033*
H3B0.94270.29730.22700.033*
H3C0.78590.24600.17140.033*
C101.52737 (11)0.01764 (8)0.06673 (9)0.0197 (2)
H10A1.53930.03850.12200.024*
H10B1.62440.04820.08980.024*
C40.95775 (14)0.10439 (9)0.36540 (10)0.0282 (3)
H4A0.98420.07010.44400.042*
H4B0.85120.11060.32500.042*
H4C1.00220.16890.38090.042*
C51.22784 (12)0.01762 (9)0.35863 (10)0.0263 (2)
H5A1.24120.01380.43680.039*
H5B1.27650.08080.37560.039*
H5C1.27040.02290.31340.039*
C111.42724 (12)0.17946 (8)0.02160 (11)0.0250 (2)
H11A1.52780.20320.04880.038*
H11B1.36780.22750.04160.038*
H11C1.38660.16860.06790.038*
C60.94484 (13)0.09035 (8)0.24995 (10)0.0252 (2)
H6A0.97100.11720.33290.038*
H6B0.98320.13230.20290.038*
H6C0.83820.08640.20750.038*
C121.47846 (13)0.10829 (10)0.21849 (11)0.0311 (3)
H12A1.57660.13660.24810.047*
H12B1.48180.04800.26320.047*
H12C1.41160.15380.23280.047*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Si10.01536 (13)0.01393 (14)0.01336 (13)0.00077 (10)0.00503 (10)0.00045 (9)
Si20.02043 (15)0.01380 (14)0.01380 (14)0.00041 (10)0.00692 (11)0.00009 (9)
Na10.0168 (2)0.0193 (2)0.0217 (2)0.00234 (15)0.00880 (17)0.00370 (15)
N10.0199 (4)0.0148 (4)0.0154 (4)0.0016 (3)0.0078 (3)0.0005 (3)
N20.0187 (4)0.0205 (4)0.0230 (4)0.0024 (3)0.0110 (4)0.0036 (3)
C10.0228 (5)0.0213 (5)0.0217 (5)0.0031 (4)0.0086 (4)0.0007 (4)
C20.0208 (5)0.0218 (5)0.0182 (5)0.0010 (4)0.0038 (4)0.0003 (4)
C30.0253 (5)0.0198 (5)0.0204 (5)0.0056 (4)0.0085 (4)0.0010 (4)
C100.0179 (5)0.0209 (5)0.0215 (5)0.0007 (4)0.0091 (4)0.0007 (4)
C40.0445 (7)0.0246 (6)0.0213 (5)0.0068 (5)0.0191 (5)0.0022 (4)
C50.0260 (6)0.0242 (6)0.0222 (5)0.0017 (5)0.0030 (4)0.0006 (4)
C110.0230 (5)0.0187 (5)0.0355 (6)0.0030 (4)0.0140 (5)0.0027 (4)
C60.0331 (6)0.0193 (5)0.0239 (5)0.0043 (4)0.0121 (5)0.0011 (4)
C120.0297 (6)0.0400 (7)0.0269 (6)0.0018 (5)0.0148 (5)0.0086 (5)
Geometric parameters (Å, º) top
Si1—N11.6878 (9)C1—H1C0.9800
Si1—C31.8825 (11)C2—H2A0.9800
Si1—C11.8871 (11)C2—H2B0.9800
Si1—C21.8990 (11)C2—H2C0.9800
Si1—Na13.3176 (5)C3—H3A0.9800
Si1—Na1i3.3185 (5)C3—H3B0.9800
Si2—N11.6874 (9)C3—H3C0.9800
Si2—C41.8798 (11)C10—C10ii1.526 (2)
Si2—C51.8890 (12)C10—H10A0.9900
Si2—C61.8904 (12)C10—H10B0.9900
Si2—Na1i3.3667 (7)C4—H4A0.9800
Si2—Na13.4814 (6)C4—H4B0.9800
Na1—N1i2.4356 (10)C4—H4C0.9800
Na1—N12.4509 (9)C5—H5A0.9800
Na1—N22.5665 (10)C5—H5B0.9800
Na1—C2i3.0415 (12)C5—H5C0.9800
Na1—Na1i3.1548 (9)C11—H11A0.9800
Na1—Si1i3.3185 (6)C11—H11B0.9800
Na1—Si2i3.3667 (7)C11—H11C0.9800
N1—Na1i2.4356 (10)C6—H6A0.9800
N2—C121.4718 (14)C6—H6B0.9800
N2—C111.4748 (14)C6—H6C0.9800
N2—C101.4767 (13)C12—H12A0.9800
C1—H1A0.9800C12—H12B0.9800
C1—H1B0.9800C12—H12C0.9800
N1—Si1—C3118.58 (5)Si1—N1—Na1i105.75 (4)
N1—Si1—C1112.81 (5)Si2—N1—Na1113.26 (4)
C3—Si1—C1103.65 (5)Si1—N1—Na1105.07 (4)
N1—Si1—C2109.73 (5)Na1i—N1—Na180.42 (3)
C3—Si1—C2105.54 (5)C12—N2—C11107.94 (9)
C1—Si1—C2105.51 (5)C12—N2—C10108.31 (8)
N1—Si1—Na145.51 (3)C11—N2—C10110.27 (8)
C3—Si1—Na1153.67 (4)C12—N2—Na1101.78 (6)
C1—Si1—Na173.46 (4)C11—N2—Na1109.96 (6)
C2—Si1—Na1100.34 (4)C10—N2—Na1117.86 (6)
C3—Si1—Na1i132.10 (4)Si1—C1—H1A109.5
C1—Si1—Na1i124.25 (4)Si1—C1—H1B109.5
C2—Si1—Na1i64.79 (3)H1A—C1—H1B109.5
Na1—Si1—Na1i56.771 (14)Si1—C1—H1C109.5
N1—Si2—C4116.24 (5)H1A—C1—H1C109.5
N1—Si2—C5114.14 (5)H1B—C1—H1C109.5
C4—Si2—C5104.49 (6)Si1—C2—H2A109.5
N1—Si2—C6110.93 (5)Si1—C2—H2B109.5
C4—Si2—C6105.31 (5)H2A—C2—H2B109.5
C5—Si2—C6104.70 (5)Si1—C2—H2C109.5
C4—Si2—Na1i128.00 (4)H2A—C2—H2C109.5
C5—Si2—Na1i127.42 (4)H2B—C2—H2C109.5
C6—Si2—Na1i67.51 (4)Si1—C3—H3A109.5
C4—Si2—Na1149.32 (4)Si1—C3—H3B109.5
C5—Si2—Na179.30 (4)H3A—C3—H3B109.5
C6—Si2—Na1102.97 (4)Si1—C3—H3C109.5
Na1i—Si2—Na154.832 (15)H3A—C3—H3C109.5
N1i—Na1—N199.58 (3)H3B—C3—H3C109.5
N1i—Na1—N2129.70 (3)N2—C10—C10ii112.28 (11)
N1—Na1—N2130.73 (3)N2—C10—H10A109.1
N1i—Na1—C2i63.70 (3)C10ii—C10—H10A109.1
N1—Na1—C2i106.50 (3)N2—C10—H10B109.1
N2—Na1—C2i96.82 (3)C10ii—C10—H10B109.1
N1i—Na1—Na1i50.00 (2)H10A—C10—H10B107.9
N1—Na1—Na1i49.58 (2)Si2—C4—H4A109.5
N2—Na1—Na1i179.70 (3)Si2—C4—H4B109.5
C2i—Na1—Na1i83.03 (3)H4A—C4—H4B109.5
N1i—Na1—Si1105.13 (3)Si2—C4—H4C109.5
N1—Na1—Si129.42 (2)H4A—C4—H4C109.5
N2—Na1—Si1118.63 (3)H4B—C4—H4C109.5
C2i—Na1—Si1135.23 (3)Si2—C5—H5A109.5
Na1i—Na1—Si161.629 (15)Si2—C5—H5B109.5
N1i—Na1—Si1i29.31 (2)H5A—C5—H5B109.5
N1—Na1—Si1i104.73 (2)Si2—C5—H5C109.5
N2—Na1—Si1i118.14 (2)H5A—C5—H5C109.5
C2i—Na1—Si1i34.40 (2)H5B—C5—H5C109.5
Na1i—Na1—Si1i61.599 (14)N2—C11—H11A109.5
Si1—Na1—Si1i123.228 (14)N2—C11—H11B109.5
N1i—Na1—Si2i28.45 (2)H11A—C11—H11B109.5
N1—Na1—Si2i108.56 (3)N2—C11—H11C109.5
N2—Na1—Si2i115.30 (3)H11A—C11—H11C109.5
C2i—Na1—Si2i87.66 (2)H11B—C11—H11C109.5
Na1i—Na1—Si2i64.434 (19)Si2—C6—H6A109.5
Si1—Na1—Si2i99.467 (17)Si2—C6—H6B109.5
Si1i—Na1—Si2i54.922 (9)H6A—C6—H6B109.5
N1i—Na1—Si2105.53 (2)Si2—C6—H6C109.5
N1—Na1—Si226.44 (2)H6A—C6—H6C109.5
N2—Na1—Si2119.53 (3)H6B—C6—H6C109.5
C2i—Na1—Si285.96 (2)N2—C12—H12A109.5
Na1i—Na1—Si260.735 (17)N2—C12—H12B109.5
Si1—Na1—Si253.868 (11)H12A—C12—H12B109.5
Si1i—Na1—Si297.166 (12)N2—C12—H12C109.5
Si2i—Na1—Si2125.168 (15)H12A—C12—H12C109.5
Si2—N1—Si1131.98 (5)H12B—C12—H12C109.5
Si2—N1—Na1i108.11 (4)
N1—Si1—Na1—N1i82.61 (5)C6—Si2—Na1—Si2i50.03 (4)
C3—Si1—Na1—N1i144.37 (8)Na1i—Si2—Na1—Si2i0.0
C1—Si1—Na1—N1i128.21 (4)C4—Si2—N1—Si114.19 (9)
C2—Si1—Na1—N1i24.95 (4)C5—Si2—N1—Si1107.58 (8)
Na1i—Si1—Na1—N1i25.47 (2)C6—Si2—N1—Si1134.44 (7)
C3—Si1—Na1—N161.76 (9)Na1i—Si2—N1—Si1132.73 (9)
C1—Si1—Na1—N1149.18 (5)Na1—Si2—N1—Si1140.13 (9)
C2—Si1—Na1—N1107.56 (5)C4—Si2—N1—Na1i118.55 (6)
Na1i—Si1—Na1—N157.14 (4)C5—Si2—N1—Na1i119.69 (5)
N1—Si1—Na1—N2123.05 (5)C6—Si2—N1—Na1i1.71 (6)
C3—Si1—Na1—N261.29 (9)Na1—Si2—N1—Na1i87.14 (5)
C1—Si1—Na1—N226.13 (4)C4—Si2—N1—Na1154.32 (5)
C2—Si1—Na1—N2129.40 (4)C5—Si2—N1—Na132.55 (6)
Na1i—Si1—Na1—N2179.82 (4)C6—Si2—N1—Na185.43 (6)
N1—Si1—Na1—C2i14.89 (5)Na1i—Si2—N1—Na187.14 (5)
C3—Si1—Na1—C2i76.65 (9)C3—Si1—N1—Si211.16 (9)
C1—Si1—Na1—C2i164.07 (5)C1—Si1—N1—Si2110.22 (7)
C2—Si1—Na1—C2i92.66 (5)C2—Si1—N1—Si2132.46 (7)
Na1i—Si1—Na1—C2i42.24 (3)Na1—Si1—N1—Si2142.42 (9)
N1—Si1—Na1—Na1i57.14 (4)Na1i—Si1—N1—Si2133.50 (9)
C3—Si1—Na1—Na1i118.89 (8)C3—Si1—N1—Na1i122.33 (5)
C1—Si1—Na1—Na1i153.69 (4)C1—Si1—N1—Na1i116.29 (5)
C2—Si1—Na1—Na1i50.42 (4)C2—Si1—N1—Na1i1.04 (5)
N1—Si1—Na1—Si1i57.14 (4)Na1—Si1—N1—Na1i84.09 (4)
C3—Si1—Na1—Si1i118.89 (8)C3—Si1—N1—Na1153.58 (4)
C1—Si1—Na1—Si1i153.69 (4)C1—Si1—N1—Na132.20 (6)
C2—Si1—Na1—Si1i50.42 (4)C2—Si1—N1—Na185.13 (5)
Na1i—Si1—Na1—Si1i0.0Na1i—Si1—N1—Na184.09 (4)
N1—Si1—Na1—Si2i111.17 (4)N1i—Na1—N1—Si2105.70 (5)
C3—Si1—Na1—Si2i172.93 (8)N2—Na1—N1—Si274.29 (6)
C1—Si1—Na1—Si2i99.65 (4)C2i—Na1—N1—Si240.45 (5)
C2—Si1—Na1—Si2i3.61 (4)Na1i—Na1—N1—Si2105.70 (5)
Na1i—Si1—Na1—Si2i54.035 (14)Si1—Na1—N1—Si2150.43 (7)
N1—Si1—Na1—Si215.79 (4)Si1i—Na1—N1—Si276.17 (5)
C3—Si1—Na1—Si245.97 (8)Si2i—Na1—N1—Si2133.58 (4)
C1—Si1—Na1—Si2133.39 (4)N1i—Na1—N1—Si1103.87 (4)
C2—Si1—Na1—Si2123.35 (4)N2—Na1—N1—Si176.14 (6)
Na1i—Si1—Na1—Si272.925 (18)C2i—Na1—N1—Si1169.12 (4)
N1—Si2—Na1—N1i80.15 (6)Na1i—Na1—N1—Si1103.87 (4)
C4—Si2—Na1—N1i129.77 (9)Si1i—Na1—N1—Si1133.41 (3)
C5—Si2—Na1—N1i129.83 (4)Si2i—Na1—N1—Si175.99 (4)
C6—Si2—Na1—N1i27.03 (5)Si2—Na1—N1—Si1150.43 (7)
Na1i—Si2—Na1—N1i23.00 (2)N1i—Na1—N1—Na1i0.0
C4—Si2—Na1—N149.62 (9)N2—Na1—N1—Na1i179.99 (4)
C5—Si2—Na1—N1150.02 (6)C2i—Na1—N1—Na1i65.25 (3)
C6—Si2—Na1—N1107.18 (6)Si1—Na1—N1—Na1i103.87 (4)
Na1i—Si2—Na1—N157.15 (5)Si1i—Na1—N1—Na1i29.54 (2)
N1—Si2—Na1—N2123.03 (6)Si2i—Na1—N1—Na1i27.88 (2)
C4—Si2—Na1—N273.41 (9)Si2—Na1—N1—Na1i105.70 (5)
C5—Si2—Na1—N226.99 (5)N1i—Na1—N2—C12148.37 (7)
C6—Si2—Na1—N2129.79 (5)N1—Na1—N2—C1231.62 (9)
Na1i—Si2—Na1—N2179.82 (4)C2i—Na1—N2—C1287.10 (7)
N1—Si2—Na1—C2i141.42 (5)Si1—Na1—N2—C1264.53 (7)
C4—Si2—Na1—C2i168.96 (8)Si1i—Na1—N2—C12115.64 (7)
C5—Si2—Na1—C2i68.56 (4)Si2i—Na1—N2—C12177.74 (6)
C6—Si2—Na1—C2i34.24 (4)Si2—Na1—N2—C122.10 (8)
Na1i—Si2—Na1—C2i84.27 (3)N1i—Na1—N2—C1197.39 (7)
N1—Si2—Na1—Na1i57.15 (5)N1—Na1—N2—C1182.62 (8)
C4—Si2—Na1—Na1i106.77 (8)C2i—Na1—N2—C11158.66 (7)
C5—Si2—Na1—Na1i152.83 (4)Si1—Na1—N2—C1149.71 (7)
C6—Si2—Na1—Na1i50.03 (4)Si1i—Na1—N2—C11130.12 (6)
N1—Si2—Na1—Si117.47 (4)Si2i—Na1—N2—C1168.02 (7)
C4—Si2—Na1—Si132.16 (8)Si2—Na1—N2—C11112.14 (6)
C5—Si2—Na1—Si1132.56 (4)N1i—Na1—N2—C1030.12 (9)
C6—Si2—Na1—Si1124.65 (4)N1—Na1—N2—C10149.86 (7)
Na1i—Si2—Na1—Si174.616 (18)C2i—Na1—N2—C1031.14 (7)
N1—Si2—Na1—Si1i108.83 (5)Si1—Na1—N2—C10177.22 (6)
C4—Si2—Na1—Si1i158.46 (8)Si1i—Na1—N2—C102.61 (8)
C5—Si2—Na1—Si1i101.14 (4)Si2i—Na1—N2—C1059.49 (7)
C6—Si2—Na1—Si1i1.66 (4)Si2—Na1—N2—C10120.35 (6)
Na1i—Si2—Na1—Si1i51.686 (12)C12—N2—C10—C10ii173.03 (11)
N1—Si2—Na1—Si2i57.15 (5)C11—N2—C10—C10ii69.05 (13)
C4—Si2—Na1—Si2i106.77 (8)Na1—N2—C10—C10ii58.31 (13)
C5—Si2—Na1—Si2i152.83 (4)
Symmetry codes: (i) x+2, y, z; (ii) x+3, y, z.
Acknowledgements top

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
References top

Bernstein, M. P., Romesberg, F. E., Fuller, D. J., Harrison, A. T., Collum, D. B., Liu, Q.-Y. & Williard, P. G. (1992). J. Am. Chem. Soc. 114, 5100–5110.

Brandenburg, K. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany.

Driess, M., Pritzkow, H., Skipinski, M. & Winkler, U. (1997). Organometallics, 16, 5108–5112.

Grüning, R. & Atwood, J. L. (1977). J. Organomet. Chem. 137, 101–111.

Henderson, K. W., Dorigo, A. E., Liu, Q.-Y. & Williard, P. G. (1997). J. Am. Chem. Soc. 119, 11855–11863.

Karl, M., Seybert, G., Massa, W., Harms, K., Agarwal, S., Maleika, R., Stelter, W., Greiner, A., Heitz, W., Neumüller, B. & Dehnicke, K. (1999). Z. Anorg. Allg. Chem. 625, 1301–1309.

Knizek, J., Krossing, I., Nöth, H., Schwenk, H. & Seifert, T. (1997). Chem. Ber. 130, 1053–1062.

Oxford Diffraction (2010). CrysAlis PRO. Oxford Diffraction Ltd, Abingdon, England.

Sarazin, Y., Coles, S. J., Hughes, D. L., Hursthouse, M. B. & Bochmann, M. (2006). Eur. J. Inorg. Chem. pp. 3211–3220.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.