1-Ethyl-2-phenyl-3-[2-(tri­methyl­sil­yl)ethyn­yl]-1H-indole

Baglai, I.; Maraval, V.; Duhayon, C.; Chauvin, R.

doi:10.1107/S1600536813012671

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 69| Part 6| June 2013| Pages o921-o922

doi:10.1107/S1600536813012671

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1-Ethyl-2-phenyl-3-[2-(trimethylsilyl)ethynyl]-1H-indole

Iaroslav Baglai,^a ^* Valérie Maraval,^b,^c Carine Duhayon ^b,^c and Remi Chauvin ^b,^c

^aDepartment of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska 64, 01033 Kyiv, Ukraine, ^bCNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and ^cUniversite de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France
^*Correspondence e-mail: iaroslav.baglai@gmail.com

(Received 29 April 2013; accepted 8 May 2013; online 18 May 2013)

The title compound, C₂₁H₂₃NSi, was synthesized by Sonogashira-type reaction of 1-ethyl-3-iodo-2-phenyl-1H-indole with trimethylsilylacetylene. The indole ring system is nearly planar [maximum atomic deviation = 0.0244 (15) Å] and is oriented at a dihedral angle of 51.48 (4)° with respect to the phenyl ring. The supramolecular aggregation is completed by weak C—H⋯π interactions of the methylene and phenyl groups with the benzene and pyrrole rings of the indole ring system. The methyl groups of the trimethylsilyl unit are equally disordered over two sets of sites.

Related literature

For background to indoles, see: Huang et al. (2004 ); Seferoğlu et al. (2007a ,b ). For the synthesis and properties of indoles, see: Ruiz et al. (2012 ); Shiri (2012 ); Hussain et al. (2011 ); Prateeptongkum et al. (2010 ); Rives et al. (2012 ).

Experimental

Crystal data

C₂₁H₂₃NSi
M_r = 317.51
Monoclinic, P 2₁ /n
a = 12.6271 (6) Å
b = 9.3928 (5) Å
c = 16.6616 (8) Å
β = 111.954 (2)°
V = 1832.83 (16) Å³
Z = 4
Mo Kα radiation
μ = 0.13 mm⁻¹
T = 100 K
0.20 × 0.20 × 0.06 mm

Data collection

Bruker Kappa APEXII diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ) T_min = 0.90, T_max = 0.99
26426 measured reflections
4320 independent reflections
3254 reflections with I > 2.0σ(I)
R_int = 0.032

Refinement

R[F² > 2σ(F²)] = 0.038
wR(F²) = 0.039
S = 1.12
3032 reflections
235 parameters
6 restraints
H-atom parameters constrained
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.30 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg4 and Cg5 are the centroids of the pyrrole and benzene rings, respectively, of indole ring system.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C10—H102⋯Cg5ⁱ	0.98	2.66	3.3512 (18)	128
C16—H161⋯Cg5ⁱⁱ	0.95	2.79	3.5122 (17)	133
C17—H171⋯Cg4ⁱⁱ	0.95	2.81	3.4515 (17)	125
Symmetry codes: (i) $[-x+{\script{5\over 2}}, y+{\script{3\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) $[-x+{\script{5\over 2}}, y+{\script{5\over 2}}, -z+{\script{3\over 2}}]$ .

Data collection: APEX2 (Bruker, 2006 ); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003 ); molecular graphics: CAMERON (Watkin et al., 1996 ); software used to prepare material for publication: CRYSTALS.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536813012671/xu5700sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813012671/xu5700Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536813012671/xu5700Isup3.cdx

Supporting information file. DOI: 10.1107/S1600536813012671/xu5700Isup4.cml

checkCIF report

Comment top

Indole is one of the three heterocycles occurring in the 20 standard natural amino-acids (in (L)-trhyptophane). Its unique bicyclic aromatic structure makes it a key rigid structural basis of one of the largest classes of alkaloids, comprising more than 4000 natural products (Huang et al., 2004; Seferoğlu et al., 2007a,b; Ruiz et al., 2012). The synthesis and functionalization of indoles have been the object of research for over one and a half century (Shiri, 2012). Few examples of Sonogashira-type reactions on the indole core have been described (Hussain et al., 2011; Prateeptongkum et al., 2010). In view of obtaining 1-ethyl-3-ethynyl-2-phenyl-1H-indole 1 b as key building block for the synthesis of highly π-frustrated carbo-benzenic chromophores (Rives et al. 2012), the title compound (1a) was synthesized (Fig. 3), and we herein report on its crystal structure.

In the molecule (Fig. 1), the indole ring is almost planar [maximum deviation for ring atoms = 0.0244 (15) Å], and the dihedral angle between the pyrrole and benzene ring of the indole system is equal to 1.83 (5)°. Methyl groups of the trimethylsilyl moieties are disordered into two positions with the corresponding occupancy of 0.5 for each part. The whole molecule is almost planar excluding methyl groups of trimethylsilyl and ethyl moieties as well as the benzene ring [maximum deviation for atoms = 0.0539 (16) Å]. The interplanar angle between indole and phenyl planes is equal to 51.48 (4)°. Inspite of the three aromatic rings of the molecule, the packing shown in Fig. 2 does not reveal any particular intermolecular π-stacking or columnar arrangement but weak C—H···π interactions (Table 1).

Related literature top

For background to indoles, see: Huang et al. (2004); Seferoğlu et al. (2007a,b). For the synthesis and properties of indoles, see: Ruiz et al. (2012); Shiri (2012); Hussain et al. (2011); Prateeptongkum et al. (2010); Rives et al. (2012).

Experimental top

The title compound 1a was prepared by the following two-step procedure (see Fig. 3) from commercially available 1-ethyl-2-phenyl-1H-indole 2 via 1-ethyl-3-iodo-2-phenyl-1H-indole 3.

1-ethyl-3-iodo-2-phenyl-1H-indole (3).

To a solution of 1-ethyl-2-phenyl-1H-indole 2 (0.5 g, 2.26 mmol) in CHCl₃ (30 ml) at 0 °C was added N-iodosuccinimide (0.535 g, 2.37 mmol) as a small portions over 5 min. The mixture was then stirred at the same temperature for 3 h. After evaporating the solvent, the residue was extracted in dichloromethane and washed with H₂O. The organic layer was separated and dried over MgSO₄. The solvent was removed under reduced pressure, and the product was purified by silica gel chromatography using a mixture of acetone and pentane (2:98) as an eluent (yield 92%, 0.72 g). R_f= 0.26.

M. p. 93 °C. ¹H NMR (CDCl₃) δ 7.59 - 7.44 (m, 6 H, H9 Ind, o-, m-, p-Ph), 7.39 - 7.22 (m, 3 H, H6, H7, H8 Ind), 4.16 (q, J = 7.1 Hz, 2 H, CH₂), 1.26 (t, J = 7.2 Hz, 3 H, CH₃). ¹³C NMR (101 MHz, CDCl₃) δ 141.4 (C2 Ind), 136.5 (C5 Ind), 132.0 (i-Ph), 130.8 (m-Ph), 130.6 (C4 Ind), 128.9 (p-Ph), 128.5 (o-Ph), 122.8, 121.6, 120.6, (C7, C8, C9 Ind), 110.0 (C6 Ind), 59.5 (C3 Ind), 39.9 (CH₂), 15.5 (CH₃). HRMS (DCI/CH₄): m/z calcd for C₁₆H₁₄NI: 347.0171, found: 347.0165.

1-ethyl-2-phenyl-3-[2-(trimethylsilyl)ethynyl]-1H-indole (1a).

CuI (42 mg, 0.21 mmol) and Pd(PPh₃)₂Cl₂ (60 mg, 0.09 mmol) were added to 1-ethyl-3-iodo-2-phenyl-1H-indole 3 (1.04 g, 3.0 mmol) under argon atmosphere. Then, freshly distilled diisopropylamine (15 ml) was added, and the mixture was stirred for 20 min, Me₃SiC≡CH (1.0 ml, 6.52 mmol) was added to the mixture and the suspension was stirred for 60 h at room temperature before adding Et₂O (20 ml). The mixture was filtrated through Celite and the filtrate was evaporated, the residue was re-dissolved in Et₂O and washed with 10% HCl, water and NaHCO₃. The resulting organic solution was dried over anhydrous MgSO₄, the solvent was removed under reduced pressure, and the brown residue was purified by silica gel chromatography using a mixture of ether and pentane (1:99) as an eluent (yield 56%, 0.53 g). R_f(99/5 = C₅H₁₂/Ether) = 0.47. The title compound was dissolved in Et₂O and CH₂Cl₂ (1:1 mixture). After slow evaporation over two days, crystals of 1a suitable for X-ray diffraction analysis were obtained.

M. p. 86 °C. ¹H NMR (400 MHz, CDCl₃) δ 7.92 (d, J = 7.4 Hz, 1 H, H9 Ind), 7.72 (d, J = 7.9 Hz, 2 H, o-Ph), 7.61- 7.33 (m, 6 H, H6, H7, H8 Ind, m-,p-Ph), 4.26 (q, J = 7.1 Hz, 2 H, CH₂), 1.38 (t, J = 7.1 Hz, 3 H, CH₃), 0.34. (s, 9 H, TMS). ¹³C NMR (101 MHz, CDCl₃) δ 144.3 (C2 Ind), 135.9 (C5 Ind), 131.1 (i-Ph), 130.2 (m-Ph), 129.4 (C4 Ind), 128.6 (p-Ph), 128.4 (o-Ph), 122.9, 120.9, 120.3 (C7, C8, C9 Ind), 110.2 (C6 Ind), 100.0, 97.4, 96.4 (C3 Ind, –C≡C–), 39.3 (CH₂), 15.3 (CH₃), 0.43 (Si(CH₃)₃). HRMS (DCI/CH₄): m/z calcd for C₂₁H₂₃NSi: 317.1600, found: 317.1614.

Computing details top

Data collection: APEX2 (Bruker, 2006); cell refinement: SAINT (Bruker, 2006); data reduction: SAINT (Bruker, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).

Figures top

	Fig. 1. The molecular structure of the title compound, showing the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Packing diagram of the title compound, viewed along the c axis.
	Fig. 3. The reaction scheme.

1-Ethyl-2-phenyl-3-[2-(trimethylsilyl)ethynyl]-1H-indole top

Crystal data top

C₂₁H₂₃NSi	F(000) = 680
M_r = 317.51	D_x = 1.151 Mg m⁻³
Monoclinic, P2₁/n	Melting point: 359 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 12.6271 (6) Å	Cell parameters from 9299 reflections
b = 9.3928 (5) Å	θ = 3–28°
c = 16.6616 (8) Å	µ = 0.13 mm⁻¹
β = 111.954 (2)°	T = 100 K
V = 1832.83 (16) Å³	Planar, colourless
Z = 4	0.20 × 0.20 × 0.06 mm

Data collection top

Bruker Kappa APEXII diffractometer	3254 reflections with I > 2.0σ(I)
Graphite monochromator	R_int = 0.032
ϕ and ω scans	θ_max = 28.1°, θ_min = 2.5°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −16→16
T_min = 0.90, T_max = 0.99	k = −12→12
26426 measured reflections	l = −22→21
4320 independent reflections

Refinement top

Refinement on F	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F² > 2σ(F²)] = 0.038	H-atom parameters constrained
wR(F²) = 0.039	[weight] = 1.0/[A₀T₀(x) + A₁T₁(x) ··· + A_n-1]*T_n-1(x)] where A_i are 0.191, 0.134 and 0.621E-01, and x = F /Fmax
S = 1.12	(Δ/σ)_max = 0.001
3032 reflections	Δρ_max = 0.31 e Å⁻³
235 parameters	Δρ_min = −0.30 e Å⁻³
6 restraints

Crystal data top

C₂₁H₂₃NSi	V = 1832.83 (16) Å³
M_r = 317.51	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 12.6271 (6) Å	µ = 0.13 mm⁻¹
b = 9.3928 (5) Å	T = 100 K
c = 16.6616 (8) Å	0.20 × 0.20 × 0.06 mm
β = 111.954 (2)°

Data collection top

Bruker Kappa APEXII diffractometer	4320 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2001)	3254 reflections with I > 2.0σ(I)
T_min = 0.90, T_max = 0.99	R_int = 0.032
26426 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	6 restraints
wR(F²) = 0.039	H-atom parameters constrained
S = 1.12	Δρ_max = 0.31 e Å⁻³
3032 reflections	Δρ_min = −0.30 e Å⁻³
235 parameters

Special details top

Refinement. Structure was refined by full-matrix least-squares procedures on F using the programs of the PC version of CRYSTALS, with 3032 reflexions [I>3.0σ(I)].

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
N1	0.99268 (10)	0.72549 (13)	0.49251 (8)	0.0196
C2	0.93192 (11)	0.79040 (15)	0.53618 (9)	0.0184
C3	0.98715 (12)	0.76670 (15)	0.62446 (9)	0.0195
C4	1.08714 (12)	0.68318 (16)	0.63574 (9)	0.0207
C5	1.08685 (11)	0.65774 (16)	0.55223 (9)	0.0211
C6	1.17008 (13)	0.57357 (17)	0.53885 (10)	0.0267
C7	1.25572 (13)	0.51899 (18)	0.61168 (11)	0.0299
C8	1.25924 (13)	0.54708 (17)	0.69552 (10)	0.0284
C9	1.17547 (13)	0.62798 (16)	0.70832 (10)	0.0243
C10	0.96037 (13)	0.71346 (17)	0.39867 (9)	0.0241
C11	1.03390 (14)	0.80491 (19)	0.36501 (10)	0.0309
C12	0.82652 (11)	0.87255 (15)	0.49367 (9)	0.0183
C13	0.73271 (13)	0.84517 (17)	0.51658 (11)	0.0261
C14	0.63450 (13)	0.92593 (18)	0.48225 (12)	0.0315
C15	0.62723 (13)	1.03523 (16)	0.42414 (11)	0.0278
C16	0.71982 (12)	1.06377 (16)	0.40118 (10)	0.0236
C17	0.81897 (12)	0.98331 (16)	0.43583 (9)	0.0206
C18	0.95193 (12)	0.81975 (15)	0.69075 (9)	0.0209
C19	0.91972 (13)	0.86562 (16)	0.74527 (9)	0.0235
Si20	0.85785 (3)	0.94562 (4)	0.81844 (3)	0.0218
C23	0.9113 (3)	1.1387 (3)	0.8372 (2)	0.0240	0.5000
C230	0.9514 (3)	1.0854 (4)	0.8847 (2)	0.0301	0.5000
C220	0.8439 (3)	0.7986 (4)	0.8949 (2)	0.0293	0.5000
C22	0.9054 (3)	0.8510 (4)	0.9200 (2)	0.0302	0.5000
C210	0.7149 (4)	1.0146 (5)	0.7538 (3)	0.0464	0.5000
C21	0.7003 (3)	0.9480 (5)	0.7620 (3)	0.0345	0.5000
H61	1.1681	0.5558	0.4825	0.0324*
H71	1.3139	0.4604	0.6047	0.0374*
H81	1.3203	0.5084	0.7444	0.0353*
H91	1.1767	0.6449	0.7647	0.0307*
H102	0.9687	0.6133	0.3855	0.0301*
H101	0.8813	0.7425	0.3710	0.0299*
H111	1.0099	0.7914	0.3042	0.0467*
H112	1.1132	0.7787	0.3925	0.0468*
H113	1.0230	0.9044	0.3756	0.0470*
H131	0.7377	0.7680	0.5565	0.0325*
H141	0.5703	0.9070	0.4976	0.0385*
H151	0.5591	1.0887	0.4017	0.0332*
H161	0.7156	1.1379	0.3613	0.0296*
H171	0.8831	1.0045	0.4207	0.0257*
H211	0.6822	0.9988	0.7107	0.0406*	0.5000
H212	0.6671	0.9920	0.7969	0.0406*	0.5000
H213	0.6727	0.8555	0.7497	0.0406*	0.5000
H2101	0.6698	0.9412	0.7211	0.0595*	0.5000
H2102	0.6816	1.0516	0.7905	0.0595*	0.5000
H2103	0.7212	1.0859	0.7171	0.0595*	0.5000
H231	0.8869	1.1873	0.7848	0.0306*	0.5000
H232	0.9907	1.1381	0.8613	0.0306*	0.5000
H233	0.8833	1.1838	0.8749	0.0306*	0.5000
H2301	0.9584	1.1579	0.8489	0.0395*	0.5000
H2302	1.0230	1.0473	0.9158	0.0395*	0.5000
H2303	0.9201	1.1220	0.9228	0.0395*	0.5000
H221	0.8782	0.7581	0.9102	0.0387*	0.5000
H222	0.9848	0.8500	0.9442	0.0387*	0.5000
H223	0.8773	0.8957	0.9578	0.0387*	0.5000
H2201	0.7966	0.7265	0.8625	0.0367*	0.5000
H2202	0.9160	0.7618	0.9260	0.0367*	0.5000
H2203	0.8131	0.8365	0.9330	0.0367*	0.5000

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0187 (5)	0.0257 (6)	0.0131 (6)	0.0054 (5)	0.0045 (4)	−0.0013 (5)
C2	0.0192 (6)	0.0204 (7)	0.0163 (7)	−0.0005 (5)	0.0073 (5)	−0.0032 (5)
C3	0.0211 (6)	0.0193 (7)	0.0174 (7)	−0.0013 (5)	0.0064 (5)	−0.0019 (5)
C4	0.0214 (7)	0.0211 (7)	0.0180 (7)	−0.0004 (5)	0.0054 (5)	−0.0022 (5)
C5	0.0186 (6)	0.0257 (7)	0.0161 (7)	0.0021 (6)	0.0031 (5)	−0.0008 (6)
C6	0.0232 (7)	0.0334 (9)	0.0225 (8)	0.0066 (6)	0.0074 (6)	−0.0021 (6)
C7	0.0214 (7)	0.0335 (9)	0.0317 (9)	0.0081 (6)	0.0063 (6)	−0.0017 (7)
C8	0.0212 (7)	0.0299 (8)	0.0247 (8)	0.0040 (6)	−0.0022 (6)	0.0017 (7)
C9	0.0258 (7)	0.0250 (7)	0.0160 (7)	−0.0006 (6)	0.0007 (5)	−0.0006 (6)
C10	0.0253 (7)	0.0314 (8)	0.0133 (7)	0.0077 (6)	0.0044 (6)	−0.0040 (6)
C11	0.0327 (8)	0.0436 (10)	0.0181 (8)	0.0098 (7)	0.0114 (6)	0.0030 (7)
C12	0.0172 (6)	0.0197 (6)	0.0164 (6)	0.0002 (5)	0.0045 (5)	−0.0045 (5)
C13	0.0244 (7)	0.0233 (7)	0.0341 (8)	0.0027 (6)	0.0147 (6)	0.0031 (6)
C14	0.0220 (7)	0.0311 (9)	0.0460 (10)	0.0015 (6)	0.0179 (7)	0.0030 (7)
C15	0.0198 (7)	0.0257 (8)	0.0353 (9)	0.0051 (6)	0.0073 (6)	−0.0019 (6)
C16	0.0228 (7)	0.0241 (7)	0.0199 (7)	−0.0001 (6)	0.0034 (5)	−0.0004 (6)
C17	0.0171 (6)	0.0275 (7)	0.0161 (7)	−0.0011 (5)	0.0049 (5)	−0.0018 (6)
C18	0.0239 (7)	0.0195 (7)	0.0179 (7)	−0.0017 (5)	0.0061 (6)	−0.0004 (5)
C19	0.0300 (7)	0.0220 (7)	0.0194 (7)	−0.0014 (6)	0.0102 (6)	−0.0011 (6)
Si20	0.02245 (19)	0.0247 (2)	0.0181 (2)	0.00257 (17)	0.00724 (15)	−0.00369 (17)
C23	0.0307 (15)	0.0225 (15)	0.0230 (16)	−0.0008 (13)	0.0148 (13)	−0.0054 (13)
C230	0.0341 (17)	0.0319 (18)	0.0258 (18)	−0.0038 (14)	0.0130 (14)	−0.0090 (15)
C220	0.0286 (16)	0.0391 (19)	0.0237 (17)	−0.0033 (15)	0.0139 (14)	−0.0031 (14)
C22	0.0373 (18)	0.0333 (18)	0.0224 (17)	−0.0011 (16)	0.0139 (15)	0.0016 (14)
C210	0.037 (2)	0.031 (2)	0.050 (3)	0.009 (2)	−0.0083 (19)	−0.012 (2)
C21	0.0283 (18)	0.036 (2)	0.039 (2)	−0.001 (2)	0.0127 (15)	0.000 (2)

Geometric parameters (Å, º) top

N1—C2	1.3811 (17)	C15—H151	0.945
N1—C5	1.3872 (18)	C16—C17	1.390 (2)
N1—C10	1.4653 (18)	C16—H161	0.951
C2—C3	1.3901 (19)	C17—H171	0.954
C2—C12	1.4709 (19)	C18—C19	1.205 (2)
C3—C4	1.438 (2)	C19—Si20	1.8366 (15)
C3—C18	1.426 (2)	Si20—C23	1.920 (3)
C4—C5	1.410 (2)	Si20—C230	1.834 (3)
C4—C9	1.402 (2)	Si20—C220	1.930 (3)
C5—C6	1.398 (2)	Si20—C22	1.804 (3)
C6—C7	1.387 (2)	Si20—C210	1.839 (4)
C6—H61	0.944	Si20—C21	1.856 (4)
C7—C8	1.406 (2)	C23—H231	0.930
C7—H71	0.960	C23—H232	0.930
C8—C9	1.382 (2)	C23—H233	0.930
C8—H81	0.959	C230—H2301	0.930
C9—H91	0.946	C230—H2302	0.930
C10—C11	1.518 (2)	C230—H2303	0.930
C10—H102	0.981	C220—H2201	0.930
C10—H101	0.969	C220—H2202	0.930
C11—H111	0.951	C220—H2203	0.930
C11—H112	0.965	C22—H221	0.930
C11—H113	0.971	C22—H222	0.930
C12—C13	1.3974 (19)	C22—H223	0.930
C12—C17	1.397 (2)	C210—H2101	0.930
C13—C14	1.382 (2)	C210—H2102	0.930
C13—H131	0.970	C210—H2103	0.930
C14—C15	1.390 (2)	C21—H211	0.930
C14—H141	0.953	C21—H212	0.930
C15—C16	1.385 (2)	C21—H213	0.930

C2—N1—C5	108.70 (11)	C16—C17—H171	119.9
C2—N1—C10	127.47 (11)	C3—C18—C19	178.42 (15)
C5—N1—C10	123.51 (11)	C18—C19—Si20	173.57 (14)
N1—C2—C3	109.21 (12)	C19—Si20—C23	106.48 (10)
N1—C2—C12	123.97 (12)	C19—Si20—C230	110.76 (12)
C3—C2—C12	126.81 (12)	C19—Si20—C220	108.16 (11)
C2—C3—C4	107.12 (12)	C23—Si20—C220	132.96 (15)
C2—C3—C18	125.82 (13)	C230—Si20—C220	108.21 (17)
C4—C3—C18	127.04 (13)	C19—Si20—C22	110.27 (12)
C3—C4—C5	106.57 (12)	C23—Si20—C22	109.80 (16)
C3—C4—C9	133.70 (14)	C230—Si20—C22	82.80 (18)
C5—C4—C9	119.73 (13)	C19—Si20—C210	108.84 (18)
C4—C5—N1	108.38 (12)	C230—Si20—C210	111.74 (18)
C4—C5—C6	121.89 (13)	C220—Si20—C210	109.0 (2)
N1—C5—C6	129.71 (13)	C22—Si20—C210	129.2 (2)
C5—C6—C7	117.15 (14)	C19—Si20—C21	108.08 (15)
C5—C6—H61	121.1	C23—Si20—C21	108.43 (18)
C7—C6—H61	121.8	C230—Si20—C21	128.55 (18)
C6—C7—C8	121.64 (14)	C220—Si20—C21	89.87 (18)
C6—C7—H71	119.2	C22—Si20—C21	113.51 (18)
C8—C7—H71	119.1	Si20—C23—H231	109.7
C7—C8—C9	120.98 (14)	Si20—C23—H232	108.8
C7—C8—H81	119.3	H231—C23—H232	109.5
C9—C8—H81	119.7	Si20—C23—H233	109.9
C4—C9—C8	118.56 (14)	H231—C23—H233	109.5
C4—C9—H91	120.4	H232—C23—H233	109.5
C8—C9—H91	121.0	Si20—C230—H2301	109.5
N1—C10—C11	112.70 (13)	Si20—C230—H2302	109.4
N1—C10—H102	107.6	H2301—C230—H2302	109.5
C11—C10—H102	109.2	Si20—C230—H2303	109.5
N1—C10—H101	108.2	H2301—C230—H2303	109.5
C11—C10—H101	109.2	H2302—C230—H2303	109.5
H102—C10—H101	110.0	Si20—C220—H2201	109.7
C10—C11—H111	108.8	Si20—C220—H2202	108.8
C10—C11—H112	110.5	H2201—C220—H2202	109.5
H111—C11—H112	109.4	Si20—C220—H2203	110.0
C10—C11—H113	109.3	H2201—C220—H2203	109.5
H111—C11—H113	108.2	H2202—C220—H2203	109.5
H112—C11—H113	110.6	Si20—C22—H221	109.0
C2—C12—C13	118.60 (13)	Si20—C22—H222	109.8
C2—C12—C17	122.61 (12)	H221—C22—H222	109.5
C13—C12—C17	118.64 (13)	Si20—C22—H223	109.6
C12—C13—C14	120.46 (15)	H221—C22—H223	109.5
C12—C13—H131	118.7	H222—C22—H223	109.5
C14—C13—H131	120.8	Si20—C210—H2101	109.6
C13—C14—C15	120.59 (14)	Si20—C210—H2102	109.4
C13—C14—H141	120.5	H2101—C210—H2102	109.5
C15—C14—H141	118.9	Si20—C210—H2103	109.4
C14—C15—C16	119.49 (14)	H2101—C210—H2103	109.5
C14—C15—H151	118.8	H2102—C210—H2103	109.5
C16—C15—H151	121.7	Si20—C21—H211	108.7
C15—C16—C17	120.15 (14)	Si20—C21—H212	109.7
C15—C16—H161	120.2	H211—C21—H212	109.5
C17—C16—H161	119.7	Si20—C21—H213	110.0
C12—C17—C16	120.67 (13)	H211—C21—H213	109.5
C12—C17—H171	119.5	H212—C21—H213	109.5

Hydrogen-bond geometry (Å, º) top

Cg4 and Cg5 are the centroids of the pyrrole and benzene rings, respectively, of indole ring system.

D—H···A	D—H	H···A	D···A	D—H···A
C10—H102···Cg5ⁱ	0.98	2.66	3.3512 (18)	128
C16—H161···Cg5ⁱⁱ	0.95	2.79	3.5122 (17)	133
C17—H171···Cg4ⁱⁱ	0.95	2.81	3.4515 (17)	125

Symmetry codes: (i) −x+5/2, y+3/2, −z+3/2; (ii) −x+5/2, y+5/2, −z+3/2.

Experimental details

Crystal data
Chemical formula	C₂₁H₂₃NSi
M_r	317.51
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	12.6271 (6), 9.3928 (5), 16.6616 (8)
β (°)	111.954 (2)
V (Å³)	1832.83 (16)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.13
Crystal size (mm)	0.20 × 0.20 × 0.06

Data collection
Diffractometer	Bruker Kappa APEXII diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2001)
T_min, T_max	0.90, 0.99
No. of measured, independent and observed [I > 2.0σ(I)] reflections	26426, 4320, 3254
R_int	0.032
(sin θ/λ)_max (Å⁻¹)	0.662

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.039, 1.12
No. of reflections	3032
No. of parameters	235
No. of restraints	6
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.31, −0.30

Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2006), SHELXS97 (Sheldrick, 2008), CRYSTALS (Betteridge et al., 2003), CAMERON (Watkin et al., 1996).

Hydrogen-bond geometry (Å, º) top

Cg4 and Cg5 are the centroids of the pyrrole and benzene rings, respectively, of indole ring system.

D—H···A	D—H	H···A	D···A	D—H···A
C10—H102···Cg5ⁱ	0.98	2.6574	3.3512 (18)	128
C16—H161···Cg5ⁱⁱ	0.95	2.7916	3.5122 (17)	133
C17—H171···Cg4ⁱⁱ	0.95	2.8136	3.4515 (17)	125

Symmetry codes: (i) −x+5/2, y+3/2, −z+3/2; (ii) −x+5/2, y+5/2, −z+3/2.

Acknowledgements

The authors would like to thank Professor Z. V. Voitenko and Professor Yu. M. Volovenko for helpful discussions.

References

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Volume 69| Part 6| June 2013| Pages o921-o922

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