5,5′-Bis[(trimethyl­silyl)meth­yl]-2,2′-bipyridine

Murray S Davies; Christopher R K Glasson; George V Meehan

doi:10.1107/S1600536807052154

. 2008 Jan 4;64(Pt 2):o364. doi: 10.1107/S1600536807052154

5,5′-Bis[(trimethylsilyl)methyl]-2,2′-bipyridine

Murray S Davies ^a,^*, Christopher R K Glasson ^a, George V Meehan ^a

PMCID: PMC2960436 PMID: 21201396

Abstract

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)°.

Related literature

For related chemistry, see: Fraser et al. (1997 ▶); Hochwimmer et al.(1998 ▶); Perkins et al. (2006 ▶); Schubert et al. (1998 ▶). For recently reported similar structures, see: Khan et al. (2004 ▶); Lindoy et al. (2204). For related literature, see: Lindoy et al. (2004 ▶).

Experimental

Crystal data

C₁₈H₂₈N₂Si₂
M _r = 328.60
Triclinic,
a = 6.279 (3) Å
b = 6.575 (3) Å
c = 14.030 (6) Å
α = 76.599 (7)°
β = 88.415 (7)°
γ = 64.859 (6)°
V = 508.4 (4) Å³
Z = 1
Mo Kα radiation
μ = 0.17 mm⁻¹
T = 293 (2) K
0.25 × 0.15 × 0.10 mm

Data collection

Bruker SMART 1000 CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.973, T _max = 0.974
4192 measured reflections
2057 independent reflections
1294 reflections with I > 2σ(I)
R _int = 0.042

Refinement

R[F ² > 2σ(F ²)] = 0.064
wR(F ²) = 0.192
S = 1.04
2057 reflections
123 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.36 e Å⁻³
Δρ_min = −0.16 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT 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 ORTEPIII (Burnett & Johnson, 1996 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536807052154/ya2054sup1.cif

e-64-0o364-sup1.cif^{(14.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807052154/ya2054Isup2.hkl

e-64-0o364-Isup2.hkl^{(99.1KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors acknowledge financial support by the Australian Research Council.

supplementary crystallographic information

Comment

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).

Experimental

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.