Acta Cryst. (2008). E64, o1950 [ doi:10.1107/S1600536808028808 ]
The title compound, C26H34NSi2+·Cl-, shows chirality at silicon. Because of its highly selective synthesis with an e.r. of >99:1 by means of a racemic resolution with mandelic acid, the free disilane is of great importance to the chemistry of highly enantiomerically enriched lithiosilanes and their trapping products. N-H
Cl hydrogen bonding is present between the protonated nitrogen atom of the piperidino group and the chloride counter-anion. The silicon-silicon distance as well as silicon-carbon and carbon-nitrogen bond lengths are in the same ranges as in other quaternary, functionalized di- and tetrasilanes.
To the enantiomerically pure (S)-1,2-Dimethyl-1,2,2-triphenyldisilan-1-(piperidinomethyl)disilane, (I), dissolved in Et2O, one equivalent of etherical HCl solution was added and stored at room temperature for 24 h. After removal of the solvent, a colourless crystalline solid of (II) remained, suitable for single crystal x-ray studies.
1H-NMR (500.1 MHz, CDCl3): δ = -4.92 (s, 3H; NCSiSiCH3), -4.80 (s, 3H; NCSiCH3), 0.95–1.05, 1.55–1.60 (m, 1H each; NCCCH2), 1.40–1.50 (m, 2H; NCCH2), 1.95–2.05, 2.05–2.15 (m, 1H each; NCCH2), 2.22–2.28, 2.30–2.37 (m, 1H each; NCH2C), 2.70–2.75, 2.80–2.85 (m, 1H each; SiCH2), 3.03–3.07, 3.12–3.18 (m, 1H each; NCH2C),7.15–7.35 (m, 15H; aromat. H).
{1H}13C-NMR (125.8 MHz, CDCl3): δ = -4.9 (1 C) (NCSiCH3), -4.8 (1 C) (NCSiSiCH3), 21.3 (1 C) (NCCCH2), 22.5, 22.6 (1 C each) (NCCH2), 49.4 (1 C) (SiCH2), 55.2, 57.4 (1 C each) (NCH2C), 128.06, 128.17, 128.37 (2 C each) (all C-m), 129.36, 129.50,129.78 (1 C each) (all C-p), 134.06, 134.64,134.77 (2 C each) (all C-o), 133.74, 133.99,134.46 (1 C each) (all C-i).
{1H}29Si-NMR (99.4 MHz, CDCl3): δ = -25.3 (1Si) (NCSi), -23.5 (1Si) (NCSiSi).
The H atoms were refined in their ideal geometric positions using the riding model approximation with Uiso(H) = 1.5Ueq(C) for methyl H atoms and of Uiso(H) = 1.2Ueq(C) for all other H atoms except atom H100 (bonded to the N atom of the piperidino group) which was refined freely.
Data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 1999); data reduction: SAINT-Plus (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Ortep-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
| Fig. 1. ORTEP plot of the asymmetric unit of (I) with displacement ellipsoids drawn at the 50% probability level. The dashed line indicates the hydrogen bond. |
| C26H34NSi2+·Cl− | F(000) = 968 |
| Mr = 452.19 | Dx = 1.201 Mg m−3 |
| Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: P 2ac 2ab | Cell parameters from 999 reflections |
| a = 10.120 (2) Å | θ = 1.9–26.0° |
| b = 13.289 (3) Å | µ = 0.26 mm−1 |
| c = 18.598 (4) Å | T = 173 K |
| V = 2501.3 (9) Å3 | Block, colourless |
| Z = 4 | 0.30 × 0.30 × 0.20 mm |
| Bruker SMART APEX CCD diffractometer | 4911 independent reflections |
| Radiation source: fine-focus sealed tube | 4808 reflections with I > 2σ(I) |
| graphite | Rint = 0.077 |
| ω–scans | θmax = 26.0°, θmin = 1.9° |
| Absorption correction: multi-scan (SADABS; Bruker, 1999) | h = −12→12 |
| Tmin = 0.926, Tmax = 0.950 | k = −16→16 |
| 45451 measured reflections | l = −22→22 |
| Refinement on F2 | Secondary atom site location: difference Fourier map |
| Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
| R[F2 > 2σ(F2)] = 0.055 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.149 | w = 1/[σ2(Fo2) + (0.0402P)2 + 1.4067P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.05 | (Δ/σ)max < 0.001 |
| 4911 reflections | Δρmax = 0.41 e Å−3 |
| 277 parameters | Δρmin = −0.34 e Å−3 |
| 0 restraints | Absolute structure: Flack (1983), 2128 Friedel pairs |
| Primary atom site location: structure-invariant direct methods | Flack parameter: 0.08 (10) |
| C26H34NSi2+·Cl− | V = 2501.3 (9) Å3 |
| Mr = 452.19 | Z = 4 |
| Orthorhombic, P212121 | Mo Kα radiation |
| a = 10.120 (2) Å | µ = 0.26 mm−1 |
| b = 13.289 (3) Å | T = 173 K |
| c = 18.598 (4) Å | 0.30 × 0.30 × 0.20 mm |
| Bruker SMART APEX CCD diffractometer | 4911 independent reflections |
| Absorption correction: multi-scan (SADABS; Bruker, 1999) | 4808 reflections with I > 2σ(I) |
| Tmin = 0.926, Tmax = 0.950 | Rint = 0.077 |
| 45451 measured reflections | θmax = 26.0° |
| R[F2 > 2σ(F2)] = 0.055 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.149 | Δρmax = 0.41 e Å−3 |
| S = 1.05 | Δρmin = −0.34 e Å−3 |
| 4911 reflections | Absolute structure: Flack (1983), 2128 Friedel pairs |
| 277 parameters | Flack parameter: 0.08 (10) |
| 0 restraints |
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 | ||
| Cl | −0.09614 (10) | 0.04149 (6) | 0.25243 (5) | 0.0361 (2) | |
| Si1 | 0.28622 (9) | 0.21087 (7) | 0.20801 (5) | 0.0249 (2) | |
| Si2 | 0.40619 (9) | 0.23973 (7) | 0.10071 (5) | 0.0276 (2) | |
| N1 | 0.0148 (3) | 0.2532 (2) | 0.25691 (15) | 0.0246 (5) | |
| C3 | −0.2128 (4) | 0.2953 (3) | 0.2978 (2) | 0.0346 (8) | |
| H3B | −0.2411 | 0.2241 | 0.2961 | 0.042* | |
| H3A | −0.2909 | 0.3378 | 0.2876 | 0.042* | |
| C17 | 0.4393 (5) | 0.0299 (3) | −0.0646 (2) | 0.0433 (10) | |
| H17 | 0.5060 | 0.0075 | −0.0968 | 0.052* | |
| C8 | 0.3754 (3) | 0.2680 (3) | 0.28642 (17) | 0.0271 (7) | |
| C2 | −0.1098 (3) | 0.3132 (3) | 0.24077 (19) | 0.0309 (7) | |
| H2A | −0.0881 | 0.3858 | 0.2387 | 0.037* | |
| H2B | −0.1452 | 0.2930 | 0.1933 | 0.037* | |
| C16 | 0.4683 (4) | 0.1011 (3) | −0.0121 (2) | 0.0374 (9) | |
| H16 | 0.5559 | 0.1262 | −0.0082 | 0.045* | |
| C6 | 0.0655 (3) | 0.2780 (3) | 0.32978 (17) | 0.0297 (7) | |
| H6A | 0.0922 | 0.3496 | 0.3312 | 0.036* | |
| H6B | 0.1446 | 0.2366 | 0.3400 | 0.036* | |
| C1 | 0.1159 (3) | 0.2715 (2) | 0.19928 (16) | 0.0273 (7) | |
| H1A | 0.1290 | 0.3452 | 0.1956 | 0.033* | |
| H1B | 0.0773 | 0.2489 | 0.1531 | 0.033* | |
| C11 | 0.4933 (4) | 0.3529 (4) | 0.4090 (2) | 0.0456 (10) | |
| H11 | 0.5315 | 0.3812 | 0.4510 | 0.055* | |
| C18 | 0.3126 (5) | −0.0077 (3) | −0.0696 (2) | 0.0435 (10) | |
| H18 | 0.2926 | −0.0565 | −0.1054 | 0.052* | |
| C19 | 0.2150 (5) | 0.0243 (3) | −0.0237 (2) | 0.0466 (10) | |
| H19 | 0.1282 | −0.0025 | −0.0273 | 0.056* | |
| C10 | 0.4387 (4) | 0.4145 (3) | 0.3574 (2) | 0.0386 (9) | |
| H10 | 0.4416 | 0.4855 | 0.3630 | 0.046* | |
| C21 | 0.3634 (3) | 0.3622 (3) | 0.05534 (19) | 0.0302 (7) | |
| C24 | 0.3080 (4) | 0.5453 (3) | −0.0126 (2) | 0.0411 (9) | |
| H24 | 0.2899 | 0.6077 | −0.0355 | 0.049* | |
| C26 | 0.3724 (4) | 0.3723 (3) | −0.0189 (2) | 0.0366 (8) | |
| H26 | 0.3978 | 0.3157 | −0.0469 | 0.044* | |
| C23 | 0.2970 (4) | 0.5373 (3) | 0.0615 (2) | 0.0420 (9) | |
| H23 | 0.2708 | 0.5938 | 0.0894 | 0.050* | |
| C9 | 0.3793 (4) | 0.3723 (3) | 0.29742 (19) | 0.0314 (7) | |
| H9 | 0.3400 | 0.4154 | 0.2627 | 0.038* | |
| C14 | 0.5853 (4) | 0.2419 (3) | 0.1259 (2) | 0.0397 (8) | |
| H14C | 0.6392 | 0.2482 | 0.0823 | 0.060* | |
| H14B | 0.6081 | 0.1794 | 0.1509 | 0.060* | |
| H14A | 0.6024 | 0.2994 | 0.1576 | 0.060* | |
| C7 | 0.2688 (4) | 0.0726 (3) | 0.2230 (2) | 0.0357 (8) | |
| H7B | 0.3567 | 0.0420 | 0.2266 | 0.054* | |
| H7C | 0.2209 | 0.0426 | 0.1825 | 0.054* | |
| H7A | 0.2198 | 0.0607 | 0.2676 | 0.054* | |
| C4 | −0.1613 (4) | 0.3193 (3) | 0.3725 (2) | 0.0394 (9) | |
| H4A | −0.1416 | 0.3920 | 0.3762 | 0.047* | |
| H4B | −0.2293 | 0.3024 | 0.4088 | 0.047* | |
| C22 | 0.3244 (4) | 0.4466 (3) | 0.0945 (2) | 0.0363 (8) | |
| H22 | 0.3166 | 0.4415 | 0.1452 | 0.044* | |
| C12 | 0.4926 (4) | 0.2503 (4) | 0.3995 (2) | 0.0435 (9) | |
| H12 | 0.5315 | 0.2080 | 0.4348 | 0.052* | |
| C5 | −0.0374 (4) | 0.2590 (3) | 0.38669 (18) | 0.0334 (8) | |
| H5A | −0.0012 | 0.2774 | 0.4344 | 0.040* | |
| H5B | −0.0595 | 0.1864 | 0.3876 | 0.040* | |
| C20 | 0.2446 (4) | 0.0968 (3) | 0.0282 (2) | 0.0368 (9) | |
| H20 | 0.1770 | 0.1196 | 0.0596 | 0.044* | |
| C15 | 0.3720 (4) | 0.1364 (3) | 0.03482 (18) | 0.0314 (8) | |
| C13 | 0.4352 (4) | 0.2081 (3) | 0.33837 (18) | 0.0338 (8) | |
| H13 | 0.4369 | 0.1372 | 0.3321 | 0.041* | |
| C25 | 0.3450 (4) | 0.4636 (3) | −0.0533 (2) | 0.0434 (9) | |
| H25 | 0.3518 | 0.4690 | −0.1041 | 0.052* | |
| H100 | −0.007 (5) | 0.180 (4) | 0.254 (3) | 0.050 (12)* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Cl | 0.0441 (5) | 0.0229 (4) | 0.0413 (5) | −0.0063 (4) | −0.0004 (4) | −0.0006 (3) |
| Si1 | 0.0270 (5) | 0.0232 (4) | 0.0246 (4) | −0.0006 (4) | 0.0003 (4) | −0.0014 (3) |
| Si2 | 0.0272 (5) | 0.0288 (4) | 0.0269 (4) | 0.0008 (4) | 0.0010 (4) | −0.0027 (4) |
| N1 | 0.0219 (13) | 0.0218 (13) | 0.0300 (13) | −0.0003 (11) | −0.0012 (11) | −0.0007 (11) |
| C3 | 0.0275 (17) | 0.0338 (18) | 0.0425 (19) | 0.0043 (15) | −0.0010 (16) | 0.0033 (16) |
| C17 | 0.059 (3) | 0.040 (2) | 0.0312 (18) | 0.018 (2) | 0.0047 (17) | −0.0007 (16) |
| C8 | 0.0232 (16) | 0.0319 (18) | 0.0263 (14) | −0.0005 (13) | 0.0004 (13) | −0.0045 (13) |
| C2 | 0.0268 (17) | 0.0288 (16) | 0.0370 (17) | 0.0046 (14) | −0.0029 (15) | 0.0047 (14) |
| C16 | 0.044 (2) | 0.0319 (19) | 0.036 (2) | 0.0022 (16) | 0.0021 (17) | 0.0010 (15) |
| C6 | 0.0299 (18) | 0.0297 (17) | 0.0296 (15) | −0.0014 (14) | −0.0039 (13) | 0.0027 (14) |
| C1 | 0.0310 (17) | 0.0254 (16) | 0.0254 (15) | −0.0010 (13) | 0.0006 (13) | 0.0002 (12) |
| C11 | 0.035 (2) | 0.067 (3) | 0.034 (2) | 0.003 (2) | −0.0007 (17) | −0.0203 (19) |
| C18 | 0.066 (3) | 0.037 (2) | 0.0277 (17) | 0.006 (2) | −0.0085 (19) | −0.0083 (15) |
| C19 | 0.046 (2) | 0.048 (2) | 0.046 (2) | 0.000 (2) | −0.0119 (19) | −0.0086 (18) |
| C10 | 0.030 (2) | 0.040 (2) | 0.046 (2) | −0.0015 (16) | 0.0077 (16) | −0.0142 (17) |
| C21 | 0.0263 (18) | 0.0330 (17) | 0.0314 (17) | −0.0021 (14) | 0.0021 (14) | 0.0005 (14) |
| C24 | 0.038 (2) | 0.035 (2) | 0.051 (2) | −0.0022 (17) | −0.0056 (17) | 0.0141 (18) |
| C26 | 0.036 (2) | 0.039 (2) | 0.0353 (19) | −0.0011 (16) | −0.0011 (16) | −0.0027 (16) |
| C23 | 0.044 (2) | 0.0252 (17) | 0.057 (2) | −0.0022 (17) | 0.0085 (19) | 0.0011 (17) |
| C9 | 0.0306 (19) | 0.0304 (17) | 0.0333 (17) | −0.0031 (14) | −0.0030 (15) | 0.0015 (15) |
| C14 | 0.0336 (19) | 0.047 (2) | 0.0386 (19) | 0.0019 (18) | −0.0008 (16) | −0.0016 (17) |
| C7 | 0.046 (2) | 0.0242 (16) | 0.0369 (18) | −0.0006 (16) | 0.0047 (16) | 0.0003 (14) |
| C4 | 0.035 (2) | 0.045 (2) | 0.0382 (19) | 0.0024 (17) | 0.0073 (16) | −0.0065 (17) |
| C22 | 0.036 (2) | 0.0367 (19) | 0.0360 (18) | −0.0055 (16) | 0.0053 (15) | 0.0010 (16) |
| C12 | 0.038 (2) | 0.061 (3) | 0.0323 (18) | 0.0150 (19) | −0.0073 (16) | 0.0049 (19) |
| C5 | 0.0322 (18) | 0.0378 (19) | 0.0302 (17) | −0.0004 (15) | 0.0056 (14) | −0.0009 (15) |
| C20 | 0.036 (2) | 0.039 (2) | 0.0353 (19) | 0.0032 (16) | 0.0016 (16) | −0.0080 (15) |
| C15 | 0.037 (2) | 0.0297 (17) | 0.0281 (17) | 0.0024 (15) | −0.0028 (14) | 0.0009 (13) |
| C13 | 0.034 (2) | 0.0348 (18) | 0.0325 (17) | 0.0053 (16) | −0.0001 (14) | 0.0002 (15) |
| C25 | 0.049 (2) | 0.044 (2) | 0.0368 (19) | −0.0060 (19) | −0.0076 (18) | 0.0085 (18) |
| Cl—H100 | 2.05 (5) | C18—H18 | 0.9500 |
| Si1—C7 | 1.867 (4) | C19—C20 | 1.397 (6) |
| Si1—C8 | 1.876 (3) | C19—H19 | 0.9500 |
| Si1—C1 | 1.910 (3) | C10—C9 | 1.386 (5) |
| Si1—Si2 | 2.3672 (13) | C10—H10 | 0.9500 |
| Si2—C14 | 1.873 (4) | C21—C26 | 1.390 (5) |
| Si2—C15 | 1.873 (4) | C21—C22 | 1.393 (5) |
| Si2—C21 | 1.884 (4) | C24—C25 | 1.375 (6) |
| N1—C6 | 1.486 (4) | C24—C23 | 1.388 (6) |
| N1—C1 | 1.502 (4) | C24—H24 | 0.9500 |
| N1—C2 | 1.521 (4) | C26—C25 | 1.400 (6) |
| N1—H100 | 1.00 (5) | C26—H26 | 0.9500 |
| C3—C2 | 1.506 (5) | C23—C22 | 1.381 (6) |
| C3—C4 | 1.518 (5) | C23—H23 | 0.9500 |
| C3—H3B | 0.9900 | C9—H9 | 0.9500 |
| C3—H3A | 0.9900 | C14—H14C | 0.9800 |
| C17—C18 | 1.379 (7) | C14—H14B | 0.9800 |
| C17—C16 | 1.392 (6) | C14—H14A | 0.9800 |
| C17—H17 | 0.9500 | C7—H7B | 0.9800 |
| C8—C13 | 1.391 (5) | C7—H7C | 0.9800 |
| C8—C9 | 1.402 (5) | C7—H7A | 0.9800 |
| C2—H2A | 0.9900 | C4—C5 | 1.511 (5) |
| C2—H2B | 0.9900 | C4—H4A | 0.9900 |
| C16—C15 | 1.389 (5) | C4—H4B | 0.9900 |
| C16—H16 | 0.9500 | C22—H22 | 0.9500 |
| C6—C5 | 1.506 (5) | C12—C13 | 1.395 (5) |
| C6—H6A | 0.9900 | C12—H12 | 0.9500 |
| C6—H6B | 0.9900 | C5—H5A | 0.9900 |
| C1—H1A | 0.9900 | C5—H5B | 0.9900 |
| C1—H1B | 0.9900 | C20—C15 | 1.398 (5) |
| C11—C12 | 1.374 (7) | C20—H20 | 0.9500 |
| C11—C10 | 1.377 (6) | C13—H13 | 0.9500 |
| C11—H11 | 0.9500 | C25—H25 | 0.9500 |
| C18—C19 | 1.374 (6) | N1—Cl | 3.031 (3) |
| C7—Si1—C8 | 109.16 (17) | C11—C10—H10 | 120.2 |
| C7—Si1—C1 | 110.05 (17) | C9—C10—H10 | 120.2 |
| C8—Si1—C1 | 109.24 (14) | C26—C21—C22 | 117.4 (3) |
| C7—Si1—Si2 | 109.48 (13) | C26—C21—Si2 | 120.9 (3) |
| C8—Si1—Si2 | 110.06 (11) | C22—C21—Si2 | 121.7 (3) |
| C1—Si1—Si2 | 108.84 (10) | C25—C24—C23 | 120.5 (4) |
| C14—Si2—C15 | 110.72 (17) | C25—C24—H24 | 119.7 |
| C14—Si2—C21 | 108.73 (17) | C23—C24—H24 | 119.7 |
| C15—Si2—C21 | 107.34 (15) | C21—C26—C25 | 121.6 (4) |
| C14—Si2—Si1 | 106.77 (13) | C21—C26—H26 | 119.2 |
| C15—Si2—Si1 | 109.76 (12) | C25—C26—H26 | 119.2 |
| C21—Si2—Si1 | 113.55 (12) | C22—C23—C24 | 119.4 (4) |
| C6—N1—C1 | 112.3 (2) | C22—C23—H23 | 120.3 |
| C6—N1—C2 | 110.5 (3) | C24—C23—H23 | 120.3 |
| C1—N1—C2 | 109.8 (2) | C10—C9—C8 | 122.0 (3) |
| C6—N1—H100 | 110 (3) | C10—C9—H9 | 119.0 |
| C1—N1—H100 | 105 (3) | C8—C9—H9 | 119.0 |
| C2—N1—H100 | 109 (3) | Si2—C14—H14C | 109.5 |
| C2—C3—C4 | 112.0 (3) | Si2—C14—H14B | 109.5 |
| C2—C3—H3B | 109.2 | H14C—C14—H14B | 109.5 |
| C4—C3—H3B | 109.2 | Si2—C14—H14A | 109.5 |
| C2—C3—H3A | 109.2 | H14C—C14—H14A | 109.5 |
| C4—C3—H3A | 109.2 | H14B—C14—H14A | 109.5 |
| H3B—C3—H3A | 107.9 | Si1—C7—H7B | 109.5 |
| C18—C17—C16 | 119.4 (4) | Si1—C7—H7C | 109.5 |
| C18—C17—H17 | 120.3 | H7B—C7—H7C | 109.5 |
| C16—C17—H17 | 120.3 | Si1—C7—H7A | 109.5 |
| C13—C8—C9 | 116.9 (3) | H7B—C7—H7A | 109.5 |
| C13—C8—Si1 | 121.2 (3) | H7C—C7—H7A | 109.5 |
| C9—C8—Si1 | 121.8 (3) | C5—C4—C3 | 109.5 (3) |
| C3—C2—N1 | 110.6 (3) | C5—C4—H4A | 109.8 |
| C3—C2—H2A | 109.5 | C3—C4—H4A | 109.8 |
| N1—C2—H2A | 109.5 | C5—C4—H4B | 109.8 |
| C3—C2—H2B | 109.5 | C3—C4—H4B | 109.8 |
| N1—C2—H2B | 109.5 | H4A—C4—H4B | 108.2 |
| H2A—C2—H2B | 108.1 | C23—C22—C21 | 121.9 (4) |
| C15—C16—C17 | 121.5 (4) | C23—C22—H22 | 119.1 |
| C15—C16—H16 | 119.3 | C21—C22—H22 | 119.1 |
| C17—C16—H16 | 119.3 | C11—C12—C13 | 120.4 (4) |
| N1—C6—C5 | 111.4 (3) | C11—C12—H12 | 119.8 |
| N1—C6—H6A | 109.3 | C13—C12—H12 | 119.8 |
| C5—C6—H6A | 109.3 | C6—C5—C4 | 111.2 (3) |
| N1—C6—H6B | 109.3 | C6—C5—H5A | 109.4 |
| C5—C6—H6B | 109.3 | C4—C5—H5A | 109.4 |
| H6A—C6—H6B | 108.0 | C6—C5—H5B | 109.4 |
| N1—C1—Si1 | 119.1 (2) | C4—C5—H5B | 109.4 |
| N1—C1—H1A | 107.5 | H5A—C5—H5B | 108.0 |
| Si1—C1—H1A | 107.5 | C19—C20—C15 | 121.2 (4) |
| N1—C1—H1B | 107.5 | C19—C20—H20 | 119.4 |
| Si1—C1—H1B | 107.5 | C15—C20—H20 | 119.4 |
| H1A—C1—H1B | 107.0 | C16—C15—C20 | 117.7 (3) |
| C12—C11—C10 | 119.9 (4) | C16—C15—Si2 | 121.9 (3) |
| C12—C11—H11 | 120.1 | C20—C15—Si2 | 120.3 (3) |
| C10—C11—H11 | 120.1 | C8—C13—C12 | 121.1 (4) |
| C19—C18—C17 | 121.0 (4) | C8—C13—H13 | 119.4 |
| C19—C18—H18 | 119.5 | C12—C13—H13 | 119.4 |
| C17—C18—H18 | 119.5 | C24—C25—C26 | 119.1 (4) |
| C18—C19—C20 | 119.3 (4) | C24—C25—H25 | 120.4 |
| C18—C19—H19 | 120.4 | C26—C25—H25 | 120.4 |
| C20—C19—H19 | 120.4 | N1—H100—Cl | 166.1 (41) |
| C11—C10—C9 | 119.6 (4) |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N1—H100···Cl | 1.00 (5) | 2.05 (5) | 3.031 (3) | 166 (4) |
| Cl—H100 | 2.05 (5) | N1—H100 | 1.00 (5) |
| Si1—Si2 | 2.3672 (13) | N1—Cl | 3.031 (3) |
| N1—H100—Cl | 166.1 (41) |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N1—H100···Cl | 1.00 (5) | 2.05 (5) | 3.031 (3) | 166 (4) |
This work was supported by the Deutsche Forschungsgemeinschaft. CS and VHG also acknowledge the Fonds der Chemischen Industrie and CD thanks the Studienstiftung des Deutschen Volkes for a doctoral scholarship.
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Functionalized lithiosilanes (Strohmann et al., 2001; Strohmann et al., 2006; Strohmann & Däschlein, 2008a,b) are versatile reagents in organic and organometallic chemistry, e.g. for the nucleophilic introduction of protecting groups, the synthesis of silyl-substituted transition metal complexes or for silicon-based polymers (Lickiss & Smith, 1995; Sekiguchi et al., 2000; Tamao & Kawachi, 1995). Especially highly enantiomerically enriched lithiosilanes are of great interest due to the increased stability of configuration at the stereogenic silicon center compared to the labile alkyllithium compounds. Yet, as the synthetic pathways to functionalized lithiosilanes are extremly limited, only six highly enantiomerically enriched systems are known until today (Colomer & Corriu, 1976; Oestreich et al., 2005; Omote et al., 2000; Sommer & Mason, 1965; Strohmann et al., 2002; Strohmann et al., 2007). Thereby the Si-Si bond cleavage of aryl substituted disilanes with lithium proved to be a potential method for the preperation of these useful compounds.
(S)-1,2-Dimethyl-1,1,2-triphenyl-1-(piperidinomethyl)disilane, (I), is an excellent starting system for the praparation of highly enantiomerically enriched lithiosilanes as it can be synthesised in an e.r. of > 99:1 by means of a racemic resolution with mandelic acid (Strohmann et al., 2002). The reaction with lithium metal results in the selective Si-Si bond cleavage and thus offers a synthetic pathway to highly enantiomerically enriched silicon-chiral di-, tri- and tetrasilanes (Strohmann et al., 2007) and -germanes (Strohmann & Däschlein, 2008b).
Treatment of (I) with HCl yields the title compound, (II), (S)-1,2-Dimethyl-1,1,2-triphenyl-1-(piperidiniummethyl)disilane chloride, as a crystalline solid. The determination of the absolute configuration of the stereogenic silicon center gave the same absolute configuration as the mandelic acid adduct published previously (Strohmann et al., 2002).
The asymmetric unit of (II) contains one molecule of the silicon-chiral disilane. Furthermore, hydrogen bonding between the hydrogen atom of the protonated nitrogen of the piperidino group and the chloride counteranion can be found (Fig. 1). The H···Cl distance (2.05 Å) and the N-H-Cl angle (166.1 °) are in the typical ranges of such hydrogen bonds (Farrugia et al., 2001). With a value of 2.3672 (13) Å, the Si-Si bond length is comparable to other known systems and is slightly larger than the sum of the covalent radii of two silicon atoms (2.33 Å). The silicon-carbon and carbon-nitrogen distances, respectively, are also in the same ranges as in previously published systems. Thereby, the longest silicon-carbon distance can be found between Si1 and C1. Due to the positive charge at the nitrogen in beta-position to Si1, the bond length to C1 is increased to 1.910 (3) Å. The other five Si-C(X) bonds (X = 7, 8, 14, 15, 21) have values between 1.873 (4) and 1.884 (4) Å (average: 1.881 Å) and thus are significantly smaller than the Si1-C1 distance but in very good agreement with the sum of the covalent radii of silicon and carbon (1.88 Å). Considering the Si1-Si2-axis, it is noteworthy to mention that the substituents at the silicon atoms do possess an almost ecliptical arrangement and therefore do not adopt the sterically less hindered staggered conformation.