Acta Cryst. (2008). E64, o364 [ doi:10.1107/S1600536807052154 ]
The molecule of the title compound, C18H28N2Si2, occupies a special position on an inversion centre. The Si-CH2-C(ipso) plane is approximately orthogonal to the plane of the pyridine rings, the corresponding dihedral angle being 82.0 (2)°.
A solution of LDA, prepared from n-BuLi (1.9 M, 1.42 ml, 2.7 mmol), and dry diisopropylamine (0.42 ml, 3.0 mmol) in dry THF (8 ml) was cooled to -78° C and a solution of 5,5'-dimethyl-2,2'-bipyridine (100 mg, 0.54 mmol) and dry HMPA (1.13 ml, 6.5 mmol) in dry THF (5 ml) was added dropwise, resulting in a deep red/brown opaque reaction mixture. This was stirred for 2 h, then trimethylsilyl chloride (217 mg, 2.0 mmol) was added, and the stirring was continued for 0.5 h more at -78° C. The resulting transparent red solution was quenched with 2 ml of absolute ethanol. Fortuitously, this solution precipitated crystals of (I) suitable for X-ray structure determination when its volume was reduced by rotary evaporation. To the remaining material, saturated NaHCO3 (10 ml) was added and the product was extracted with ethyl acetate (3 × 40 ml). The combined organic fractions were dried over anhydrous Na2SO4 and the solvent removed under vacuum. The resulting solid was purified by chromatography on deactivated silica gel, affording (I) as a greasy white solid (142 mg, 80%). δH (300 MHz; CDCl3) 0.02 (18H, s, SiMe3) 2.12 (4H, s, CH2), 7.45 (2H, dd, J = 7.8, 1.8 Hz, H-4,4'), 8.22 (2H, d, J = 7.8 Hz, H-3,3'), 8.34 (2H, d, 1.8 Hz, H-6,6'); δC (75 MHz; CDCl3) 2.06 (SiMe3), 23.92 (CH2), 120.16, 136.11, 136.18, 148.22, 152.21.
All aromatic and methylene H atoms were located in the difference map and refined with isotropic thermal parameters [C—H 0.94 (2) - 1.03 (3) Å]. Methyl H atoms were positioned geometrically and refined in a riding model approximation with C—H bond distances of 0.96 Å and Uiso(H) = 1.5 Ueq of the parent C atom.
Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001) and XPREP (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Burnett & Johnson (1996); software used to prepare material for publication: WinGX (Farrugia, 1999).
![[Figure 1]](./ya2054fig1thm.gif)
| Fig. 1. ORTEP (Burnett and Johnson (1996), Farrugia (1997)) drawing of (I) with displacement ellipsoids shown at 50% probability level. Only the non-hydrogen atoms in the asymmetric unit are labelled; unlabelled atoms are derived from the corresponding labelled atoms by means of the (1 - x, 3 - y, -z) transformation. |
![[Figure 2]](./ya2054fig2thm.gif)
| Fig. 2. Crystal packing diagram of (I) viewed down the a axis of the crystal. |
| C18H28N2Si2 | Z = 1 |
| Mr = 328.60 | F000 = 178 |
| Triclinic, P1 | Dx = 1.073 Mg m−3 |
| Hall symbol: -P 1 | Mo Kα radiation λ = 0.71069 Å |
| a = 6.279 (3) Å | Cell parameters from 1147 reflections |
| b = 6.575 (3) Å | θ = 0.9–26.4º |
| c = 14.030 (6) Å | µ = 0.17 mm−1 |
| α = 76.599 (7)º | T = 293 (2) K |
| β = 88.415 (7)º | Prism, colourless |
| γ = 64.859 (6)º | 0.25 × 0.15 × 0.10 mm |
| V = 508.4 (4) Å3 |
| Bruker SMART 1000 CCD area-detector diffractometer | 2057 independent reflections |
| Radiation source: fine-focus sealed tube | 1294 reflections with I > 2σ(I) |
| Monochromator: graphite | Rint = 0.042 |
| T = 293(2) K | θmax = 26.4º |
| φ and ω scans | θmin = 3.0º |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −7→7 |
| Tmin = 0.973, Tmax = 0.974 | k = −8→8 |
| 4192 measured reflections | l = −17→17 |
| 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)] = 0.064 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.192 | w = 1/[σ2(Fo2) + (0.093P)2] where P = (Fo2 + 2Fc2)/3 |
| S = 1.04 | (Δ/σ)max = 0.007 |
| 2057 reflections | Δρmax = 0.36 e Å−3 |
| 123 parameters | Δρmin = −0.16 e Å−3 |
| Primary atom site location: structure-invariant direct methods | Extinction correction: none |
| C18H28N2Si2 | γ = 64.859 (6)º |
| Mr = 328.60 | V = 508.4 (4) Å3 |
| Triclinic, P1 | Z = 1 |
| a = 6.279 (3) Å | Mo Kα |
| b = 6.575 (3) Å | µ = 0.17 mm−1 |
| c = 14.030 (6) Å | T = 293 (2) K |
| α = 76.599 (7)º | 0.25 × 0.15 × 0.10 mm |
| β = 88.415 (7)º |
| Bruker SMART 1000 CCD area-detector diffractometer | 2057 independent reflections |
| Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1294 reflections with I > 2σ(I) |
| Tmin = 0.973, Tmax = 0.974 | Rint = 0.042 |
| 4192 measured reflections |
| R[F2 > 2σ(F2)] = 0.064 | 123 parameters |
| wR(F2) = 0.192 | H atoms treated by a mixture of independent and constrained refinement |
| S = 1.04 | Δρmax = 0.36 e Å−3 |
| 2057 reflections | Δρmin = −0.16 e Å−3 |
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. An empirical absorption correction determined with SADABS (Sheldrick, 1996) was applied to the data. The data integration and reduction were undertaken with SAINT and XPREP (Bruker, 2001). The data reduction included the application of Lorentz and polarization corrections. The reflection data were merged including Fridel opposites. The structure was solved in the space group P-1 by direct methods with SHELXS97 (Sheldrick, 1997) within the WinG-X (Farrugia, 1999) interface and extended and refined with SHELXL97 (Sheldrick 1997). Anisotropic thermal parameters were refined for the non-hydrogen atoms. All aromatic and methylene H atoms were located and refined with isotropic thermal parameters. Methyl H atoms were constrained as riding atoms, fixed to the parent C atom with a distance of 0.96 Å. Uiso values were set to 1.5 Ueq of the parent C atom. 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 | 0.78941 (12) | 0.61211 (12) | 0.82038 (5) | 0.0664 (3) | |
| C1 | 0.5188 (4) | 1.3836 (4) | 0.52943 (15) | 0.0544 (5) | |
| N1 | 0.7386 (3) | 1.2150 (4) | 0.53910 (15) | 0.0681 (6) | |
| C4 | 0.6028 (4) | 0.9417 (4) | 0.63513 (16) | 0.0594 (6) | |
| C2 | 0.3355 (4) | 1.3408 (5) | 0.57193 (18) | 0.0646 (7) | |
| C5 | 0.7751 (5) | 1.0028 (5) | 0.59098 (19) | 0.0686 (7) | |
| C6 | 0.6608 (5) | 0.6974 (5) | 0.69012 (18) | 0.0660 (7) | |
| C3 | 0.3787 (5) | 1.1207 (5) | 0.62426 (18) | 0.0673 (7) | |
| C9 | 0.5840 (5) | 0.8130 (5) | 0.8897 (2) | 0.0951 (9) | |
| H9A | 0.5359 | 0.9699 | 0.8525 | 0.143* | |
| H9B | 0.6620 | 0.7910 | 0.9517 | 0.143* | |
| H9C | 0.4478 | 0.7823 | 0.9009 | 0.143* | |
| C7 | 0.8328 (6) | 0.3086 (5) | 0.8742 (2) | 0.1086 (11) | |
| H7B | 0.8969 | 0.2606 | 0.9412 | 0.163* | |
| H7C | 0.9400 | 0.2082 | 0.8371 | 0.163* | |
| H7A | 0.6838 | 0.3008 | 0.8719 | 0.163* | |
| C8 | 1.0830 (5) | 0.6243 (6) | 0.8206 (2) | 0.1070 (11) | |
| H8A | 1.0637 | 0.7764 | 0.7865 | 0.160* | |
| H8B | 1.1908 | 0.5123 | 0.7882 | 0.160* | |
| H8C | 1.1446 | 0.5904 | 0.8871 | 0.160* | |
| H6A | 0.773 (4) | 0.589 (4) | 0.6581 (18) | 0.074 (8)* | |
| H6B | 0.513 (5) | 0.676 (4) | 0.6947 (18) | 0.087 (8)* | |
| H5 | 0.923 (4) | 0.883 (4) | 0.5873 (17) | 0.075 (7)* | |
| H3 | 0.243 (5) | 1.082 (4) | 0.6515 (19) | 0.093 (8)* | |
| H2 | 0.179 (4) | 1.470 (4) | 0.5684 (16) | 0.067 (7)* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Si1 | 0.0679 (5) | 0.0709 (5) | 0.0656 (5) | −0.0393 (4) | 0.0016 (3) | −0.0070 (3) |
| C1 | 0.0476 (13) | 0.0684 (14) | 0.0500 (12) | −0.0274 (12) | 0.0054 (10) | −0.0148 (10) |
| N1 | 0.0537 (12) | 0.0677 (13) | 0.0784 (14) | −0.0267 (10) | 0.0164 (10) | −0.0096 (11) |
| C4 | 0.0635 (15) | 0.0713 (15) | 0.0509 (12) | −0.0374 (13) | 0.0049 (11) | −0.0123 (11) |
| C2 | 0.0457 (13) | 0.0728 (17) | 0.0686 (15) | −0.0243 (13) | 0.0056 (11) | −0.0077 (13) |
| C5 | 0.0546 (15) | 0.0663 (16) | 0.0765 (17) | −0.0221 (13) | 0.0141 (12) | −0.0104 (14) |
| C6 | 0.0720 (18) | 0.0705 (16) | 0.0665 (16) | −0.0400 (15) | 0.0085 (13) | −0.0187 (13) |
| C3 | 0.0567 (15) | 0.0804 (18) | 0.0696 (16) | −0.0381 (14) | 0.0088 (12) | −0.0107 (13) |
| C9 | 0.108 (2) | 0.116 (2) | 0.0779 (19) | −0.060 (2) | 0.0187 (17) | −0.0319 (18) |
| C7 | 0.127 (3) | 0.084 (2) | 0.110 (2) | −0.052 (2) | −0.006 (2) | −0.0014 (18) |
| C8 | 0.080 (2) | 0.136 (3) | 0.113 (3) | −0.061 (2) | −0.0108 (18) | −0.015 (2) |
| Si1—C9 | 1.853 (3) | C5—H5 | 0.94 (2) |
| Si1—C7 | 1.864 (3) | C6—H6A | 0.95 (2) |
| Si1—C6 | 1.878 (3) | C6—H6B | 1.00 (3) |
| Si1—C8 | 1.879 (3) | C3—H3 | 1.03 (3) |
| C1—N1 | 1.339 (3) | C9—H9A | 0.9600 |
| C1—C2 | 1.385 (3) | C9—H9B | 0.9600 |
| C1—C1i | 1.483 (4) | C9—H9C | 0.9600 |
| N1—C5 | 1.340 (3) | C7—H7B | 0.9600 |
| C4—C3 | 1.382 (4) | C7—H7C | 0.9600 |
| C4—C5 | 1.390 (3) | C7—H7A | 0.9600 |
| C4—C6 | 1.501 (4) | C8—H8A | 0.9600 |
| C2—C3 | 1.376 (3) | C8—H8B | 0.9600 |
| C2—H2 | 0.98 (2) | C8—H8C | 0.9600 |
| C9—Si1—C7 | 111.14 (16) | Si1—C6—H6B | 105.3 (15) |
| C9—Si1—C6 | 109.21 (14) | H6A—C6—H6B | 110 (2) |
| C7—Si1—C6 | 107.55 (14) | C2—C3—C4 | 120.9 (2) |
| C9—Si1—C8 | 110.33 (15) | C2—C3—H3 | 120.9 (15) |
| C7—Si1—C8 | 109.30 (16) | C4—C3—H3 | 118.1 (15) |
| C6—Si1—C8 | 109.25 (13) | Si1—C9—H9A | 109.5 |
| N1—C1—C2 | 121.3 (2) | Si1—C9—H9B | 109.5 |
| N1—C1—C1i | 116.9 (2) | H9A—C9—H9B | 109.5 |
| C2—C1—C1i | 121.8 (2) | Si1—C9—H9C | 109.5 |
| C1—N1—C5 | 117.7 (2) | H9A—C9—H9C | 109.5 |
| C3—C4—C5 | 115.2 (2) | H9B—C9—H9C | 109.5 |
| C3—C4—C6 | 123.4 (2) | Si1—C7—H7B | 109.5 |
| C5—C4—C6 | 121.4 (2) | Si1—C7—H7C | 109.5 |
| C3—C2—C1 | 119.6 (2) | H7B—C7—H7C | 109.5 |
| C3—C2—H2 | 120.8 (13) | Si1—C7—H7A | 109.5 |
| C1—C2—H2 | 119.5 (13) | H7B—C7—H7A | 109.5 |
| N1—C5—C4 | 125.4 (2) | H7C—C7—H7A | 109.5 |
| N1—C5—H5 | 115.7 (15) | Si1—C8—H8A | 109.5 |
| C4—C5—H5 | 118.0 (15) | Si1—C8—H8B | 109.5 |
| C4—C6—Si1 | 115.70 (17) | H8A—C8—H8B | 109.5 |
| C4—C6—H6A | 111.0 (14) | Si1—C8—H8C | 109.5 |
| Si1—C6—H6A | 105.7 (14) | H8A—C8—H8C | 109.5 |
| C4—C6—H6B | 108.8 (15) | H8B—C8—H8C | 109.5 |
| Symmetry codes: (i) −x+1, −y+3, −z+1. |
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As a part of our work on cryptates derived from 5,5'-disubstituted-2,2'-bipyridines (Perkins et al., 2006), we have studied methyl functionalization reactions of 5,5'-dimethyl-2,2'-bipyridine as a model for similar chemistry proposed for its more complex analogue, 5,5"'-dimethyl-2,2':5',5":2",2"'-quaterpyridine. In contrast to the previous report by Schubert et al. (1998), we have been able to promote bis-lithiation of 5,5'-dimethyl-2,2'-bipyridine with lithium diisopropylamide (LDA) in THF by use of a coordinating co-solvent, hexamethylphosphoramide (HMPA). Subsequent bis-silylation with trimethylsilyl chloride afforded (I) in good yield.
The molecule of the title compound (Fig.1) occupies a special position in the inversion centre. The SiMe3 groups are trans disposed relative to the plane of the two pyridyl rings giving the molecule a zigzag shape (Fig. 2). The dihedral angle between the plane of the bipyridyl rings, and that of trimethylsilylmethyl substituent, as defined by Si1—C6—C4, is 82.0 (2)°.
The molecules in crystal show stacking arrangement with methylenetrimethylsilyl groups of the adjacent molecules oriented in the same direction (Fig. 2).