6-(1-Methyl­ethyl)-12-phenyl-5,6,7,12-tetra­hydro­dibenz[c,f][1,5]aza­silocine

Kei Goto; Akihiro Fukushima; Takayuki Kawashima

doi:10.1107/S1600536809050909

. 2009 Dec 4;66(Pt 1):o20. doi: 10.1107/S1600536809050909

6-(1-Methylethyl)-12-phenyl-5,6,7,12-tetrahydrodibenz[c,f][1,5]azasilocine

Kei Goto ^a,^*, Akihiro Fukushima ^b, Takayuki Kawashima ^b

PMCID: PMC2980245 PMID: 21580084

Abstract

The title compound, C₂₃H₂₅NSi, has an eight-membered silicon-containing heterocyclic ring with an intramolecular N⋯Si close contact, the transannular distance of which is 2.6294 (18) Å. The resulting geometry about the Si atom is distorted trigonal-bypyramidal, with the N and H atoms occupying apical sites. The dihedral angle between the aromatic rings fused to the eight-membered ring is 63.27 (7)°.

Related literature

For highly coordinated organosilanes, see: Brellère et al. (1986 ▶); Carré et al. (1997 ▶); Paton et al. (1977 ▶); Woning & Verkade (1991 ▶); Yoshida et al. (2006 ▶). For a related structure, see: Saruhashi et al. (2001 ▶).

Experimental

Crystal data

C₂₃H₂₅NSi
M _r = 343.53
Monoclinic,
a = 9.756 (7) Å
b = 10.269 (7) Å
c = 18.912 (12) Å
β = 92.745 (3)°
V = 1893 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.13 mm⁻¹
T = 120 K
0.20 × 0.20 × 0.10 mm

Data collection

Rigaku Mercury CCD diffractometer
Absorption correction: multi-scan (REQAB; Jacobson, 1998 ▶) T _min = 0.975, T _max = 0.987
11962 measured reflections
3278 independent reflections
2798 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.041
wR(F ²) = 0.100
S = 1.08
3278 reflections
232 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.30 e Å⁻³

Data collection: CrystalClear (Rigaku, 2004 ▶); cell refinement: CrystalClear data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPIII (Burnett & Johnson, 1996 ▶); software used to prepare material for publication: yadokari-XG (Wakita, 2005 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809050909/is2498sup1.cif

e-66-00o20-sup1.cif^{(22.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809050909/is2498Isup2.hkl

e-66-00o20-Isup2.hkl^{(160.8KB, hkl)}

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

Acknowledgments

This work was partly supported by the Global COE Program (Chemistry) and Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan. KG is grateful to Tokuyama Science Foundation for financial support. We also thank Tosoh Finechem Corporation for the generous gifts of alkyllithiums.

supplementary crystallographic information

Comment

Highly coordinated hydrosilanes have been of great interest for their unique structures and reactivities. It has been known that, in highly coordinated monohydrosilanes, the Si—H bond has high affinity for equatorial position (Brellère et al., 1986) and there are only a few examples with the Si—H bond at the apical position (Woning & Verkade, 1991). A dibenz[c,f][1,5]azasilocine framework has been utilized for the synthesis of various highly coordinated silicon compounds (Paton et al., 1977; Carré et al., 1997; Yoshida et al., 2006). Recently, we reported the synthesis and structural characterization of a pentacoordinated monohydrosilane bearing this molecular framework with the apical Si—H bond (Saruhashi et al., 2001). As a further investigation of this work, the crystal structure of the title new hydrosilane is reported.

The title compound was synthesized by the reaction of N,N-bis(2-bromobenzyl)isopropylamine (Carré et al., 1997) with n-butyllithium followed by treatment with phenylsilane. The molecular structure of the title compound is shown in Fig. 1. It was found that the geometry around the silicon atom is that of a distorted trigonal bypyramid with the sum of the equatorial C—Si—C bond angles of 346.3°. The SiH hydrogen atom occupies the apical site in spite of its lower apicophilicity than that of a phenyl group, which is similar to the related N-butyl compound we previously reported (Saruhashi et al., 2001). The Si···N transannular distance is 2.6294 (18) Å, which is slightly longer than that of the N-butyl derivative [2.516 (2) Å] probably because of the steric repulsion between the isopropyl group and the phenyl ring.

Experimental

A solution of n-butyllithium in hexane (1.6 M; 4.2 ml, 6.7 mmol) was added dropwise to a solution of N,N-bis(2-bromobenzyl)isopropylamine (1.25 g, 3.16 mmol) in ether (3 ml) at 233 K. The solution was stirred at the same temperature for 30 min and then allowed to warm to room temperature. After stirring for additional 2 h, the solution was cooled to 233 K, and a solution of phenylsilane (345 mg, 3.19 mmol) in ether (2 ml) was added dropwise. The mixture was allowed to warm to room temperature, and stirred overnight. After addition of water, the mixture was extracted with ether, and the organic layer was dried over anhydrous magnesium sulfate. After filtration and removal of the solvent, the residue was purified by gel permeation liquid chromatography (eluting with chloroform) and then recrystallization from hexane to give the title compound (101 mg, 0.295 mmol, 9.3%) as colorless crystals. Physical data: m.p. 354.1–355.8 K (decomposition); ¹NMR (400 MHz, CDCl₃, 300 K): δ 0.76 (br, 6H), 2.53 (br, 1H), 3.78 (s, 4H), 5.53 (brs, 1H), 7.12–7.32 (m, 9H), 7.51 (br, 2H), 7.72 (br, 2H). Anal. Calcd for C₂₃H₂₅NSi: C 80.41, H 7.34, N 4.08%. Found: C 80.19, H 7.48, N, 3.94%.