metal-organic compounds
catena-Poly[sodium-μ2-(N,N,N′,N′-tetramethylethane-1,2-diamine)-κ2N:N′-sodium-bis[μ2-bis(trimethylsilyl)azanido-κ2N:N]]
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
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
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Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell 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
10.1107/S1600536812045126/pk2451sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536812045126/pk2451Isup2.hkl
All experimental manipulations were performed under an atmosphere of argon using either standard Schlenk techniques or a MBraun 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).
fitted with an 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):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.
Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell
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).[Na2(C6H18NSi2)2(C6H16N2)] | F(000) = 532 |
Mr = 482.98 | Dx = 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 |
Oxford Diffraction Gemini S diffractometer | 3436 independent reflections |
Radiation source: fine-focus sealed tube | 3064 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.012 |
ω scans | θmax = 29.1°, θmin = 3.0° |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | h = −13→13 |
Tmin = 0.942, Tmax = 1.000 | k = −18→18 |
8332 measured reflections | l = −16→16 |
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(Fo2) + (0.0371P)2 + 0.2964P] where P = (Fo2 + 2Fc2)/3 |
3436 reflections | (Δ/σ)max = 0.001 |
135 parameters | Δρmax = 0.37 e Å−3 |
0 restraints | Δρmin = −0.18 e Å−3 |
[Na2(C6H18NSi2)2(C6H16N2)] | V = 1492.4 (3) Å3 |
Mr = 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)° |
Oxford Diffraction Gemini S diffractometer | 3436 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | 3064 reflections with I > 2σ(I) |
Tmin = 0.942, Tmax = 1.000 | Rint = 0.012 |
8332 measured reflections |
R[F2 > 2σ(F2)] = 0.023 | 0 restraints |
wR(F2) = 0.067 | H-atom parameters constrained |
S = 1.07 | Δρmax = 0.37 e Å−3 |
3436 reflections | Δρmin = −0.18 e Å−3 |
135 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
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* |
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) |
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)] |
Mr | 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) |
Tmin, Tmax | 0.942, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8332, 3436, 3064 |
Rint | 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 |
Δρmax, Δρmin (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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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.