CRYSTAL AND MOLECULAR STRUCTURE OF DICHLORO[(Z)-2-CHLORO-2-PHENYLVINYL](ACETONE)TELLURIUM(IV)
Robinson L. Camillo (PG)a, I. Caracelli (PQ)a, Rodrigo L.O.R. Cunha (PG)b, João V. Comasseto (PQ)b and J. Zukerman-Schpector (PQ)a,b.
a Laboratório de Cristalografia, Estereodinâmica e Modelagem Molecular-Departamento de Química, UFSCar. b Instituto de Química-USP.
Palavras-chave: telúrio, difração de raios-X, estereoquímica
Organyltellurium trichlorides are quite insoluble in the solvents usually used for NMR studies. On the other hand, the corresponding diorganotellurium dichlorides are quite soluble, specially in chloroform. For this reason the organyltellurium trichloride obtained from the reaction of TeCl4 with phenylethyne was treated with an excess of acetone giving the corresponding a-tellurium acetone dichloride which, in turn, was recrystallized from methylene dichloride to give the title compound. As the NMR analysis give no clue on the stereochemistry of the compound an X-ray crystal structure analysis was undertaken.
Crystal data were measured on a Enraf-Nonius CAD-4 Mach3 diffractometer using the q-2q scan technique, at room temperature, and graphite monochromated MoKa radiation. Data were collected up to q = 260 and corrected for Lorentz-polarization and absorption effects. The structure was solved by the heavy-atom Patterson method (SHELXS-86 [1]) and difference Fourier syntheses and refined anisotropically by full-matrix least-squares on F2 (SHELXL-97 [2]). H-atoms were located on stereochemical grounds and refined with fixed geometry, each riding on a carrier atom, with an isotropic displacement parameter equal to 1.5 (for methyl H atoms) or 1.2 (for the other H atoms) times the value of the equivalent isotropic displacement parameter of the atom to which they were attached. Drawing was done using ZORTEP [3].
Crystal Data: C11 H11 Cl3 O Te, fw = 393.15, monoclinic. P21/n, a = 12.661(1), b = 6.033(1), c = 18.494(1)Å, b = 96.19(1)0, V = 1404.4(3) Å3, Z = 4, dx = 1.859 g cm-3, m = 2.666 mm-1, S = 1.044, R1 = 0.0252 for 2195 reflections with I>2s(I) and 146 refined parameters.
Discussion: distances and angles involving the Te atom are: Te-C1 2.077(4), Te-C9 2.130(4), TeCl1 2.5158(11), Te-Cl2 2.4918(12) Å, C1-Te-C9 98.32(14), C1-Te-Cl2 87.16(11), C9-Te-Cl2 88.03(13), C1-Te-Cl1 86.47(11), C9-Te-Cl1 87.26(13), Cl1-Te-Cl2 171.46(4)0. The coordination around the TeIV atom is consistent with a pseudo-trigonal bipyramidal bond configuration with two Cl atoms occupying axial positions while the C atoms and the lone pair of electrons occupy the equatorial positions.
This configuration is in complete agreement with the valence shell electron-pair repulsion model (VSEPR). The average quadruple angle, (E4, for the Te lone pair of electrons is 112.60, a value typical for TeX4E configurations [4]. The Te ( Cl1 and Te ( Cl2 axial lengths are 0.13 and 0.16 Å longer than the sum of the normal covalent radii, 2.36 Å, as expected for pseudo-trigonal bipyramidal coordinations. The Te atom makes three secondary interactions, one intermolecular Te...Cl2A (symmetry operation: A = 1.5-x, 0.5+y, 0.5-z) of 3.637(1) Å, and two intramolecular: Te...O = 2.842(3) Å and Te...Cl3 = 3.209(1) Å. These distances are less than the sum of the van der Waals radii of Te, O and Cl. Taking into account this three interactions, the Te atom is seven coordinated with a distorted C3v symmetry. Besides the Te...Cl secondary interaction the molecules are also related by a C-H...O hydrogen bond: O1...C6B = 3.360(6) Å, O1...H6B = 2,567 Å, O1...H6B-C6B = 143.540, (symmetry operation: B = -x, 1-y, -z)
[1] Sheldrick, G.M. (1990). SHELXS-86. Program for Solving Crystal Structures. Acta Crystallogr. A46, 467.
[2] Sheldrick, G.M. (1997). SHELXL-97. Program for the Refinement of Crystal Structures. University of Göttingen, Germany.
[3] Zsolnay. L. (1995). ZORTEP. An Interactive Molecular Graphics Program. University of Heidelberg, Germany.
[4] Zukerman-Schpector, J. et al. (1996) Acta Crystallogr. C52, 2772. (and references therein).
FAPESP, CNPq