PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2010 September 1; 66(Pt 9): o2442.
Published online 2010 August 28. doi:  10.1107/S1600536810034173
PMCID: PMC3007930

Tetra­kis(4-tert-butyl­benz­yl)silane

Abstract

The title compound, C44H60Si, was prepared as an inter­nal standard for diffusion-ordered NMR spectroscopy. The Si atom lies on a special position with An external file that holds a picture, illustration, etc.
Object name is e-66-o2442-efi7.jpg site symmetry.

Related literature

For applications of the title compound in NMR spectroscopy, see: Li et al. (2009 [triangle]). For similar structures in the same space group, see: Liao et al. (2002 [triangle]); Laliberté et al. (2004 [triangle]). For a previously reported NMR standard, see: Monroe et al. (2010 [triangle]). For a description of the Cambridge Structural Database, see: Allen (2002 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-o2442-scheme1.jpg

Experimental

Crystal data

  • C44H60Si
  • M r = 617.01
  • Tetragonal, An external file that holds a picture, illustration, etc.
Object name is e-66-o2442-efi8.jpg
  • a = 17.394 (2) Å
  • c = 6.3613 (6) Å
  • V = 1924.7 (4) Å3
  • Z = 2
  • Cu Kα radiation
  • μ = 0.72 mm−1
  • T = 295 K
  • 0.31 × 0.15 × 0.12 mm

Data collection

  • Enraf–Nonius CAD-4 diffractometer
  • 5204 measured reflections
  • 1738 independent reflections
  • 1056 reflections with I > 2σ(I)
  • R int = 0.036
  • 3 standard reflections every 113 reflections intensity decay: 2%

Refinement

  • R[F 2 > 2σ(F 2)] = 0.041
  • wR(F 2) = 0.135
  • S = 1.02
  • 1738 reflections
  • 106 parameters
  • H-atom parameters constrained
  • Δρmax = 0.13 e Å−3
  • Δρmin = −0.11 e Å−3

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 [triangle]); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]) and Mercury (Macrae et al., 2006 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810034173/su2206sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810034173/su2206Isup2.hkl

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

Acknowledgments

This work was supported in part by funds provided by the University of North Carolina at Charlotte. Support for REU participant RMK was provided by the National Science Foundation, award number CHE-0851797. Many helpful discussions with T. Blake Monroe are gratefully acknowledged.

supplementary crystallographic information

Comment

The title compound was prepared as an internal standard for diffusion-ordered NMR spectroscopy. A recent paper on this subject (Li et al., 2009) suggests an internal standard method for correlating diffusion coefficients with formula weights. The title compound was chosen because its shape in solution both approximates that of a spheroid and is similar to that of the species being studied. In addition, it neither reacts with the species under study nor gives interfering NMR signals.

The molecular structure of the title molecule is illustrated in Fig. 1. The molecule sits on a fourfold rotoinversion axis, with the Si atom located at the point of inversion and the four ligands arranged tetrahedrally around the Si atom. The crystal packing of the title compound, viewed along the c axis, is illustrated in Fig. 2.

The space group, P42/n, is relatively rare, comprising fewer than 700 of the half-million-plus structures in the Cambridge Structural Database [Version 5.31; Allen, 2002]. Similar structures which crystallized in the same space group include tetrakis(4-N-t-Butyl-N-aminoxylphenyl)silane (Liao et al., 2002) and tetrakis(4-(Ethoxycarbonylamino)phenyl)silane bis(dioxane) clathrate (Laliberté et al., 2004).

We have previously reported on the crystal structure of another NMR standard of smaller molecular weight, bis(2-naphthylmethyl)diphenylsilane (Monroe et al., 2010).

Experimental

The synthesis of the title compound is descibed in Fig. 3. A dry, 250 ml Schlenk flask, equipped with a magnetic stirbar, was charged with 4-tertbutyltoluene (I) (7.13 g, 50 mmol), potassium tert-butoxide (6.72 g, 55 mmol), then purged with nitrogen. 100 ml of freshly distilled dry THF was added and the reaction was cooled to 195 K. n-BuLi (23.91 ml, 2.3M, 55 mmol) was then added dropwise. The Schlenk flask was then capped and kept at 233 K overnight. The solution was again cooled to 195 K and 2.09 ml (1.68 g, 10 mmol) of tetrachlorosilane was added dropwise. The reaction mixture was allowed to warm to room temperature and stirred for two hours. The mixture was then quenched with deionized water and extracted three times with petroleum ether. The combined organic layers were dried with magnesium sulfate, filtered, and evaporated. Bulb-to-bulb distillation gave a tan solid, which was recrystallized from petroleum ether to yield pure colorless crystals of tetrakis(4-tert-butylbenzyl)silane (II) (3.45 g, 56% recovery).

mp 407–409 K; 1H NMR (Toluene-d8, 300 MHz): 1.27 (s)9H, 2.14 (s)2H, 6.85 (d)2H, 7.20 (d)2H. 13C NMR (Toluene-d8, 300 MHz): 31.66, 34.20, 20.71, 124.96, 128.75, 129.52, 147.13. GC/MS (70ev) m/z: 469.4, 57.1

Refinement

The H-atoms were included in calculated positions and treated as riding atoms: C-H = 0.93, 0.97 and 0.96 Å for aromatic CH, CH2, and CH3 H-atoms, respectively, with Uiso(H) = k × Ueq(C), where k = 1.5 for CH3 H-atoms, and k = 1.2 for all other H-atoms.

Figures

Fig. 1.
View of title molecule with 50% probability displacement ellipsoids [Symmetry codes: (i) -x + 1/2, -y + 1/2, z (ii) y, -x + 1/2, -z + 1/2 (iii) -y + 1/2, x, -z + 1/2].
Fig. 2.
Crystal packing diagram of the title compound viewed along the c axis.
Fig. 3.
Synthesis scheme.

Crystal data

C44H60SiDx = 1.065 Mg m3
Mr = 617.01Cu Kα radiation, λ = 1.54184 Å
Tetragonal, P42/nCell parameters from 25 reflections
Hall symbol: -P 4bcθ = 7.8–35.3°
a = 17.394 (2) ŵ = 0.72 mm1
c = 6.3613 (6) ÅT = 295 K
V = 1924.7 (4) Å3Prism, colorless
Z = 20.31 × 0.15 × 0.12 mm
F(000) = 676

Data collection

Enraf–Nonius CAD-4 diffractometerθmax = 67.4°, θmin = 3.6°
non–profiled ω/2θ scansh = −20→20
5204 measured reflectionsk = −20→15
1738 independent reflectionsl = −7→0
1056 reflections with I > 2σ(I)3 standard reflections every 113 reflections
Rint = 0.036 intensity decay: 2%

Refinement

Refinement on F2H-atom parameters constrained
Least-squares matrix: fullw = 1/[σ2(Fo2) + (0.0761P)2 + 0.1124P] where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.041(Δ/σ)max < 0.001
wR(F2) = 0.135Δρmax = 0.13 e Å3
S = 1.02Δρmin = −0.11 e Å3
1738 reflectionsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
106 parametersExtinction coefficient: 0.0033 (6)
0 restraints

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
Si0.250.250.250.0599 (4)
C40.50538 (12)0.30509 (12)0.4293 (4)0.0780 (7)
H40.52630.28560.55290.094*
C10.33661 (10)0.25820 (11)0.0742 (4)0.0674 (7)
H1A0.35070.20690.02880.081*
H1B0.32170.2868−0.05020.081*
C50.54015 (10)0.36783 (10)0.3360 (3)0.0535 (5)
C70.44050 (11)0.35854 (12)0.0714 (4)0.0668 (6)
H70.41930.3779−0.05190.08*
C80.61357 (11)0.40291 (11)0.4257 (4)0.0624 (6)
C20.40700 (10)0.29575 (10)0.1652 (4)0.0580 (5)
C60.50509 (12)0.39375 (12)0.1556 (4)0.0674 (6)
H60.52550.43650.08760.081*
C30.44105 (12)0.27021 (12)0.3468 (4)0.0837 (8)
H30.420.22810.41630.1*
C90.62982 (15)0.48273 (14)0.3328 (5)0.0951 (9)
H9A0.6340.47890.18270.143*
H9B0.67710.50230.38960.143*
H9C0.58850.5170.36820.143*
C100.68066 (12)0.35026 (15)0.3687 (5)0.0992 (9)
H10A0.6720.30010.42690.149*
H10B0.72750.37110.42490.149*
H10C0.68480.34650.21860.149*
C110.60896 (17)0.41111 (18)0.6619 (5)0.1047 (9)
H11A0.56740.4450.69770.157*
H11B0.65640.4320.7140.157*
H11C0.60020.36160.72410.157*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Si0.0473 (4)0.0473 (4)0.0852 (9)000
C40.0612 (12)0.0722 (13)0.101 (2)−0.0089 (11)−0.0143 (12)0.0413 (13)
C10.0543 (11)0.0616 (11)0.0863 (18)0.0010 (9)0.0016 (11)0.0004 (11)
C50.0496 (10)0.0501 (10)0.0609 (12)0.0033 (8)0.0116 (10)0.0070 (9)
C70.0658 (12)0.0750 (13)0.0596 (15)−0.0063 (10)0.0042 (10)0.0141 (11)
C80.0584 (11)0.0644 (12)0.0645 (15)−0.0057 (9)0.0067 (10)0.0059 (10)
C20.0477 (10)0.0504 (10)0.0759 (14)0.0042 (8)0.0086 (10)0.0056 (10)
C60.0688 (12)0.0698 (13)0.0638 (14)−0.0169 (10)0.0105 (12)0.0169 (11)
C30.0617 (12)0.0677 (13)0.122 (2)−0.0127 (10)−0.0093 (14)0.0472 (14)
C90.0946 (17)0.0790 (15)0.112 (2)−0.0315 (13)−0.0090 (16)0.0155 (15)
C100.0538 (12)0.111 (2)0.133 (3)0.0025 (13)0.0030 (14)−0.0136 (19)
C110.118 (2)0.120 (2)0.0760 (19)−0.0328 (17)0.0054 (17)−0.0061 (17)

Geometric parameters (Å, °)

Si—C1i1.882 (2)C8—C111.512 (3)
Si—C1ii1.882 (2)C8—C101.527 (3)
Si—C1iii1.882 (2)C8—C91.535 (3)
Si—C11.882 (2)C2—C31.372 (3)
C4—C31.377 (3)C6—H60.93
C4—C51.382 (3)C3—H30.93
C4—H40.93C9—H9A0.96
C1—C21.504 (3)C9—H9B0.96
C1—H1A0.97C9—H9C0.96
C1—H1B0.97C10—H10A0.96
C5—C61.375 (3)C10—H10B0.96
C5—C81.526 (3)C10—H10C0.96
C7—C21.374 (3)C11—H11A0.96
C7—C61.387 (3)C11—H11B0.96
C7—H70.93C11—H11C0.96
C1i—Si—C1ii110.68 (7)C3—C2—C7116.09 (19)
C1i—Si—C1iii107.08 (14)C3—C2—C1122.34 (18)
C1ii—Si—C1iii110.68 (7)C7—C2—C1121.6 (2)
C1i—Si—C1110.68 (7)C5—C6—C7122.44 (19)
C1ii—Si—C1107.08 (14)C5—C6—H6118.8
C1iii—Si—C1110.68 (7)C7—C6—H6118.8
C3—C4—C5122.7 (2)C2—C3—C4121.94 (19)
C3—C4—H4118.7C2—C3—H3119
C5—C4—H4118.7C4—C3—H3119
C2—C1—Si117.14 (16)C8—C9—H9A109.5
C2—C1—H1A108C8—C9—H9B109.5
Si—C1—H1A108H9A—C9—H9B109.5
C2—C1—H1B108C8—C9—H9C109.5
Si—C1—H1B108H9A—C9—H9C109.5
H1A—C1—H1B107.3H9B—C9—H9C109.5
C6—C5—C4115.05 (19)C8—C10—H10A109.5
C6—C5—C8123.50 (17)C8—C10—H10B109.5
C4—C5—C8121.4 (2)H10A—C10—H10B109.5
C2—C7—C6121.8 (2)C8—C10—H10C109.5
C2—C7—H7119.1H10A—C10—H10C109.5
C6—C7—H7119.1H10B—C10—H10C109.5
C11—C8—C5111.41 (19)C8—C11—H11A109.5
C11—C8—C10109.4 (2)C8—C11—H11B109.5
C5—C8—C10108.13 (17)H11A—C11—H11B109.5
C11—C8—C9107.9 (2)C8—C11—H11C109.5
C5—C8—C9111.83 (18)H11A—C11—H11C109.5
C10—C8—C9108.09 (19)H11B—C11—H11C109.5

Symmetry codes: (i) −y+1/2, x, −z+1/2; (ii) −x+1/2, −y+1/2, z; (iii) y, −x+1/2, −z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SU2206).

References

  • Allen, F. H. (2002). Acta Cryst. B58, 380–388. [PubMed]
  • Enraf–Nonius (1994). CAD-4 EXPRESS Enraf–Nonius, Delft, The Netherlands.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Farrugia, L. J. (1999). J. Appl. Cryst.32, 837–838.
  • Harms, K. & Wocadlo, S. (1995). XCAD4 University of Marburg, Germany.
  • Laliberté, D., Maris, T. & Wuest, J. (2004). Can. J. Chem.82, 386–398.
  • Li, D., Kagan, G., Hopson, R. & Williard, P. G. (2009). J. Am. Chem. Soc.131, 5627–5634. [PMC free article] [PubMed]
  • Liao, Y., Baskett, M., Lahti, P. & Palacio, F. (2002). Chem. Commun. pp. 252–253. [PubMed]
  • Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst.39, 453–457.
  • Monroe, T. B., Thomas, A. A., Jones, D. S. & Ogle, C. A. (2010). Acta Cryst. E66, o132. [PMC free article] [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography