4-(Dimethyl­amino)phenyl ethynyl telluride

Joan Farran; Angel Alvarez-Larena; Joan F Piniella; Mario V Capparelli

doi:10.1107/S1600536809009404

. 2009 Mar 25;65(Pt 4):o812–o813. doi: 10.1107/S1600536809009404

4-(Dimethylamino)phenyl ethynyl telluride

Joan Farran ^a, Angel Alvarez-Larena ^a, Joan F Piniella ^a, Mario V Capparelli ^a,^*

PMCID: PMC2968982 PMID: 21582534

Abstract

The title compound, C₁₀H₁₁NTe, is the first organyl ethynyl telluride, R—Te—C C—H, to be structurally characterized. In the L-shaped molecule, the aryl moiety, viz. Me₂NC₆H₄Te, is almost perpendicular to the Te—C C—H fragment. The Te—Csp ² bond [2.115 (3) Å] is significantly longer than the Te—Csp bond [2.041 (4) Å]. The Te—C C group is approximately linear [Te—C—C = 178.5 (4)° and C C = 1.161 (5) Å], while the coordination at the Te atom is angular [C—Te—C = 95.92 (14)°]. In the crystal structure, there are Csp—H⋯N hydrogen bonds which are perpendicular to the CNMe₂ group; the N atom displays some degree of pyramidalization. Centrosymmetrically related pairs of molecules are linked by Te⋯π(aryl) interactions, with Te⋯Cg = 3.683 (4) Å and Csp—Te⋯Cg = 159.1 (2)° (Cg is the centroid of the benzene ring). These interactions lead to the formation of zigzag ribbons which run along c and are approximately parallel to (110).

Related literature

For general background, see: Dabdoub et al. (1998 ▶); Gillespie & Hargittai (1991 ▶); Kauffmann & Ahlers (1983 ▶); Murai et al. (1994 ▶); Petragnani (1994 ▶); Potapov & Trofimov (2005 ▶); Schulz Lang et al. (2006 ▶); Yoshimatsu (2005 ▶); Zukerman-Schpector & Haiduc (2001 ▶). For related structures, see: Farran et al. (2002 ▶). For details of the synthesis, see: Brandsma (1988 ▶); Petragnani et al. (1975 ▶).

Experimental

Crystal data

C₁₀H₁₁NTe
M _r = 272.80
Triclinic,
a = 7.8857 (7) Å
b = 8.3851 (8) Å
c = 9.3364 (9) Å
α = 65.788 (2)°
β = 66.922 (1)°
γ = 83.444 (2)°
V = 517.18 (8) Å³
Z = 2
Mo Kα radiation
μ = 2.82 mm⁻¹
T = 294 K
0.36 × 0.30 × 0.10 mm

Data collection

Bruker SMART APEX diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ▶) T _min = 0.403, T _max = 0.754
3574 measured reflections
2401 independent reflections
2080 reflections with I > 2σ(I)
R _int = 0.012

Refinement

R[F ² > 2σ(F ²)] = 0.034
wR(F ²) = 0.087
S = 1.04
2401 reflections
110 parameters
H-atom parameters constrained
Δρ_max = 0.75 e Å⁻³
Δρ_min = −0.35 e Å⁻³

Data collection: SMART (Bruker, 2002 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809009404/bg2241sup1.cif

e-65-0o812-sup1.cif^{(14.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809009404/bg2241Isup2.hkl

e-65-0o812-Isup2.hkl^{(115.5KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯N1ⁱ	0.93	2.48	3.379 (6)	163

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Symmetry code: (i) Inline graphic .

Acknowledgments

The authors gratefully acknowledge the financial support of the European Union (project No. CI1*.0574.ES). JF thanks the Generalitat de Catalunya for an FI grant and MVC thanks the Ministerio de Educación y Cultura of Spain for a sabbatical grant (project No. SAB95-0281). The sample studied was kindly provided by Professor L. Torres-Castellanos. The X-ray measurements were carried out at the Servei de Difracció de Raigs X (UAB).

supplementary crystallographic information

Comment

Although organotellurium compounds have attracted considerable interest as reagents and intermediates in organic synthesis (Petragnani, 1994), only a limited number of compounds with mono- and ditelluroethyne cores, R—Te—C≡CH and R—Te—C≡C-Te—R', have been reported, in spite of the potential reactivity of the acetylene unit towards addition reactions. We recently reported the syntheses and crystal structures of several symmetrical (R = R') bis(aryltelluro)ethynes, Ar—Te—C≡C-Te—Ar (Farran et al., 2002). On the other hand, only five R—Te—C≡CH derivatives have been prepared so far, with R = Me, Et, ⁱPr, n-Bu and Ph (Kauffmann & Ahlers, 1983; Dabdoub et al., 1998; Potapov & Trofimov, 2005; Yoshimatsu, 2005), and none has been structurally characterized (in addition, molecular orbital calculations for R = HC≡C were carried out by Murai et al., 1994). Here we describe the crystal structure of the title compound (R = p-Me₂NC₆H₄), the first of an organyl ethynyl telluride to be reported.

The structure analysis showed that the crystal contains discrete L-shaped molecules of the title compound (Figure 1), in which the aryl moiety, Me₂NC₆H₄Te, is almost perpendicular to the Te—C≡C-H fragment (cf. C—Te—C angle, Table 1), but bent ca 13° towards the C12—C13 side of the ring (cf. C—Te—C—C angles, Table 1), probably to optimize the C—H···N interaction (see below).

As expected, the Te—C(sp²) bond is significantly longer than the Te—C(sp) one. The Te—C≡C moiety is approximately linear, while the coordination at the Te atom is angular, as predicted by the valence-shell electron-pair repulsion (VSEPR) model for an AX₂E₂ molecule (Gillespie & Hargittai, 1991). The values of these geometric parameters (Table 1) are similar to the ranges observed in several bis(arytelluro)ethynes, Ar—Te—C≡C-Te—Ar (Farran et al., 2002), viz. Te—C(sp²), 2.103 (5)–2.142 (6) Å; Te—C(sp), 2.021 (6)–2.058 (6) Å; C≡C, 1.166 (12)–1.203 (11) Å and C—Te—C, 94.2 (3)–97.2 (2)°, which are substantially smaller than the tetrahedral value (109.5°) due to the repulsion of the lone pairs of electrons on the bonded ones.

In the crystal structure the molecules are linked by C(sp)—H···N hydrogen bonds (Table 2) which are perpendicular to the CNMe₂ group. The N atom displays some degree of pyramidalization: it is 0.123 (5) Å out of the plane of the three C atoms, towards the H atom. There are also Te···π(aryl) interactions, similar to those described by Zukerman-Schpector & Haiduc (2001) or Schulz Lang et al. (2006) for Te(IV) compounds, in which centrosymmetrically related pairs of molecules are at Te···Cg 3.683 (4) Å and C(sp)—Te···Cg 159.1 (2)° (Cg = centroid of the phenyl ring at 1 - x, -y, 1 - z). These interactions lead to the formation of zigzag ribbons, made of pairs of chains, which run along c and are approximately parallel to (110) (Figure 2).

Experimental

Ethynyl magnesium bromide, HC≡CMgBr, was prepared according to published procedures (Brandsma, 1988). The corresponding diaryl ditelluride, (Me₂NC₆H₄Te)₂, was synthesized as reported elsewhere (Petragnani et al., 1975). A dark solution of the diaryl ditelluride (2.0 mmol, 0.94 g) in 40 ml of THF was treated dropwise with bromine (2.0 mmol, 0.32 g, 0.10 ml) in 10 ml of benzene, at 0°C, in N₂ atmosphere, while efficient cooling was applied. The Grignard reagent was then added dropwise. Gradual disappearance of the dark color of the solution was observed until it finally became almost colorless when about 10% excess of the reagent was added. After stirring for 30 min at room temperature, the solution was diluted with 50 ml of low boiling point petroleum ether, treated with aqueous NH₄Cl and washed with brine. The organic layer was dried over magnesium sulfate and the solvents were evaporated. The residue was purified by flash chromatography (silica gel/hexane). Yield 51%. Crystals suitable for X-ray analysis were obtained by slow evaporation of a chloroform solution. The specimen used for data collection was air-protected with a thin coat of Loctite epoxy adhesive.