Crystal structure of bis(4-dimethylaminophenyl)telluride, (4-Me2NC6H4)2Te

C16H20N2Te, triclinic, P1 (No. 2), a = 9.9090(6) A, b = 10.405(3) A, c = 15.803(2) A, = 102.29(1)°, = 94.142(7)°, = 94.05(1)°, V = 1581.7 A, Z = 4, Rgt(F) = 0.031, wRref(F ) = 0.087, T = 298 K. Source of material The precursor (4-Me2NC6H4)2TeCl2 was syntesized by refluxing in dioxane (50 ml), for 3 h, a mixture of TeCl4 [1] (1.46 g, 5.42 mmol) with 4-Me2NC6H4HgCl [2] (3.92 g, 11.0 mmol). Cooling at 273 K with stirring precipitated a white Hg2Cl:dioxane complex, which was filtered off. The solution was dried and the green-yellowish solid was extracted with chloroform to obtain (4-Me2NC6H4)2TeCl2 (1.62 g, 3.69 mmol). Recrystallization from acetone produced yellow needles, mp 460 K – 461 K with decomposition (461 K – 462 K [3]). The (4-Me2NC6H4)2TeCl2 (1.30 g, 2.96 mmol) was mixed with melted Na2S·9H2O (9.00 g, 37.5 mmol), which produced an exothermic reaction. The mixture was kept at 383 K for 10 min and then cooled with water (20 ml) at 273 K. The orange-yellow crystalline solid was filtered off and washed with cold water (0.163 g, 0.444 mmol, 15%). Crystals suitable for X-ray diffraction were obtained from slow evaporation of a solution in chloroform. Discussion Within our program of synthetic and structural studies of organotellurium compounds [4], we prepared the title compound and determined its crystal structure. The asymmetric unit contains two independent molecules of (4-Me2NC6H4)2Te. The molecules are V-shaped, as predicted by the valence-shell electron-pair repulsion (VSEPR) model for an AX2E2 molecule [5]. Within experimental error (i.e. 3 e.s.d.’s) the four Te—C distances are equal (average: 2.110 A), and their values are comparable to the standard value of 2.116(20) A for Te-C(aryl) [6], and to 2.110(3) and 2.112(3) A, observed in (4-MeOC6H4)2Te [7], and to 2.105(5) A and 2.125(5) A, in (2-PhC6H4)2Te [8]. As expected, the C–Te–C angles (average: 97.1°) are considerably smaller than the tetrahedral value (109.5°), because of the repulsion of the lone pairs of electrons on the bonded pairs. These angles are similar to 96.2(2)°, found in (2-PhC6H4)2Te [8] and to 96.3(2)° in [2-(4-MeOC6H4N: CH)C6H4]2Te [9]. The bond lengths in the organic moieties are in good agreement with the tabulated values [6]. Both independent molecules are essentially similar. The main difference lies in the orientation of the ring systems [ring/plane/ring dihedral angles: C1n/C–Te1–C/C2n, 79.1(2)° and 1.4(2)°; C3n/C–Te2–C/C4n, 81.2(2)° and 85.4(2)°], probably because of the packing forces, which are entirely of van der Waals type. Z. Kristallogr. NCS 217 (2002) 427–429 427 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: pale brown prism, size 0.15 × 0.18 × 0.39 mm Wavelength: Mo K radiation (0.71069 A) : 18.70 cm Diffractometer, scan mode: Enraf Nonius CAD4, /2 2 max: 49.94° N(hkl)measured, N(hkl)unique: 5570, 5570 Criterion for Iobs, N(hkl)gt: Iobs > 2 (Iobs), 3701 N(param)refined: 343 Programs: SHELXS-97 [10], SHELXL-97 [11], ORTEP-3 [12], WinGX [13] Table 1. Data collection and handling. H(12) 2i 0.0373 –0.4625 0.5978 0.077 H(13) 2i –0.1693 –0.4532 0.6526 0.079 H(15) 2i –0.1364 –0.0609 0.6829 0.080 H(16) 2i 0.0748 –0.0701 0.6320 0.080 H(171) 2i –0.4706 –0.3484 0.7278 0.142 H(172) 2i –0.3362 –0.4119 0.7475 0.142 H(173) 2i –0.3988 –0.4298 0.6513 0.142 H(181) 2i –0.4543 –0.1453 0.7434 0.135 H(182) 2i –0.3711 –0.0860 0.6778 0.135 H(183) 2i –0.3090 –0.0732 0.7737 0.135 H(22) 2i 0.0029 –0.2429 0.4457 0.068 H(23) 2i –0.0628 –0.2249 0.3075 0.068 Table 2. Atomic coordinates and displacement parameters (in A). Atom Site x y z Uiso