1,1′-Di-tert-butyl-2,2′,3,3′,4,4′,5,5′-octa­ethyl-1,1′-bis­tannole

Takuya Kuwabara; Masaichi Saito

doi:10.1107/S1600536811022951

. 2011 Jun 18;67(Pt 7):m949. doi: 10.1107/S1600536811022951

1,1′-Di-tert-butyl-2,2′,3,3′,4,4′,5,5′-octaethyl-1,1′-bistannole

Takuya Kuwabara ^a, Masaichi Saito ^a,^*

PMCID: PMC3152095 PMID: 21836931

Abstract

The title compound, [Sn₂(C₄H₉)₂(C₁₂H₂₀)₂], has two 1-stannacyclopentadiene skeletons related by inversion symmetry located at the mid-point of the Sn—Sn bond [2.7682 (2) Å]. Thus, the asymmetric unit comprises one half-molecule. The planarity of the stannacyclopentadiene ring is illustrated by the dihedral angle of 0.3 (1)°, defined by the C₄ and C—Sn—C planes. To avoid steric repulsion, the two stannole rings are oriented in an anti fashion through the Sn—Sn bond. These structural features are similar to those of other bistannoles.

Related literature

For the synthesis and X-ray diffraction analysis of bi(1,1-stannole)s whose carbon atoms of the five-membered rings have phenyl groups, see: Saito et al. (2002 ▶, 2005 ▶). For related literature on bi-, oligo- and poly-(1,1-metallole)s, see: Haga et al. (2008 ▶); Kanno et al. (1998 ▶); Kim & Woo (2002 ▶); Saito & Yoshioka (2005 ▶); Saito et al. (2010 ▶); Sohn et al. (1999 ▶, 2003 ▶); Yamaguchi & Tamao (1998 ▶); Yamaguchi et al. (1997 ▶, 1999 ▶).

Experimental

Crystal data

[Sn₂(C₄H₉)₂(C₁₂H₂₀)₂]
M _r = 680.20
Monoclinic,
a = 8.7161 (5) Å
b = 16.5999 (9) Å
c = 11.7913 (6) Å
β = 100.827 (1)°
V = 1675.67 (16) Å³
Z = 2
Mo Kα radiation
μ = 1.51 mm⁻¹
T = 100 K
0.25 × 0.10 × 0.05 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (XPREP; Bruker, 2008 ▶) T _min = 0.835, T _max = 0.927
9015 measured reflections
3636 independent reflections
3387 reflections with I > 2σ(I)
R _int = 0.017

Refinement

R[F ² > 2σ(F ²)] = 0.017
wR(F ²) = 0.043
S = 1.04
3636 reflections
161 parameters
H-atom parameters constrained
Δρ_max = 0.43 e Å⁻³
Δρ_min = −0.42 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ▶); cell refinement: SAINT (Bruker, 2008 ▶); data reduction: SAINT and XPREP (Bruker, 2008 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: XSHELL (Bruker, 2008) ▶; software used to prepare material for publication: XCIF (Bruker, 2008) ▶.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811022951/kp2332sup1.cif

e-67-0m949-sup1.cif^{(17.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811022951/kp2332Isup2.hkl

e-67-0m949-Isup2.hkl^{(177.4KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811022951/kp2332Isup3.cml

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

Table 1. Selected geometric parameters (Å, °).

Sn1—C1	2.1416 (15)
Sn1—C4	2.1475 (16)
Sn1—C5	2.1906 (16)

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C1—Sn1—C4

83.75 (6)

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was partially supported by Grant-in-Aids for Scientific Research (B) (No. 22350015 to MS) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan. MS acknowledges a research grant from Mitsubishi Foundation. TK acknowledges the Sasakawa Scientific Research Grant from the Japan Science Society

supplementary crystallographic information

Comment

The group 14 metalloles has received much attention as good precursors of their polymers that reveal interesting optical properties (Yamaguchi et al., 1998; Haga et al., 2008) as well as their anion species, which are heavier congeners of the cyclopentadienyl anion (Saito et al., 2005). After the synthesis of several oligo(1,1-silole)s and poly(1,1-silole)s (Yamaguchi et al., 1997, 1999); Kanno et al., 1998; Sohn et al., 1999), they have been used as building blocks of organic electroluminescent devices (Kim & Woo (2002)). Poly(1,1-germole)s have also been synthesized (Sohn et al., 2003). In contrast, as for tin analogues, only a few reports on the synthesis of oligo(1,1-stannole)s have appeared, so far (Haga et al., 2008). We report herein the molecular structure of the title compound, which is a novel bi(1,1-stannole) bearing ethyl groups on the carbon atoms of the five-membered rings.

The X-ray diffraction analysis reveals that the title compound, bis(1-tert-butyl-2,3,4,5-tetraethylstannacyclopentadienyl) (I), has two planar five-membered rings with C–C bond alternations. The molecule is centrosymmetric with an inversion center in the middle of Sn–Sn bond, and hence a half moiety of the molecule was refined. The two stannole rings are oriented in an anti fashion through the Sn–Sn bond to avoid steric repulsion. The Sn–Sn bond length of 2.7689 (2) Å is in a normal range of the corresponding single bond, as was observed in other bi(1,1-stannole)s (2.7844 (7) and 2.7822 (7) Å (Saito et al., 2002, 2005). The structural features of the title compound are therefore quite similar to those of other bi(1,1-stannole)s that have electronically neutral tin centers, and substituents on the ring carbon atoms little affect the structural feartures of bi(1,1-stannole)s.

Experimental

A diethyl ether solution (0.55 mL) of tert-butyl chloride (0.94 M, 0.52 mmol) was added to a diethyl ether solution (7 mL) of 2,2',3,3',4,4',5,5'-octaethyl-1,1'-dilithiobistannole (Saito et al., 2010) (118.8 mg, 0.203 mmol) at room temperature, and the mixture was stirred for 3 h. After removal of volatile substances, the residue was degassed by freeze-pump-thaw cycles and sealed. In a glovebox, materials insoluble in hexane were removed by filtration and the filtrate was concentrated to provide a crude product. Recrystallisation of the crude product from diethyl ether afforded colourless crystals of bis(1-tert-butyl-2,3,4,5-tetraethylstannacyclopentadienyl) (107.7 mg, 0.154 mmol, 76%). (1) ¹H NMR (C₆D₆, 400 MHz) δ 1.02 (t, J = 7 Hz, 12H), 1.19 (t, J = 7 Hz, 12H), 1.40(s, J_Sn–H = 73 Hz, 18H), 2.33(q, J = 7 Hz, 8H), 2.41–2.60(m, 8H); ¹³C NMR (101 MHz, C₆D₆) δ 18.44 (q, J_Sn–C = 13 Hz), 22.61 (t, J_Sn–C = 48 Hz), 26.85 (t, J_Sn–C = 54 Hz), 30.71 (s, J_Sn–C = 22, 314, 328 Hz), 32.54 (t), 145.74 (s, J_Sn–C = 26, 287, 301 Hz), 152.92 (s, J_Sn–C = 21, 63 Hz); ¹¹⁹Sn NMR (186 MHz, C₆D₆)δ -68.8 (J_Sn–C = 301 Hz, J_Sn–Sn = 948 Hz).