Gas-phase vibrational spectrum and molecular geometry of TeCl4

Abstract

The gas electron diffraction pattern and the infrared spectrum of gaseous TeCl ₄ have been measured and ab initio molecular orbital calculations performed for the TeCl ₄ molecule using second-order Møller–Plesset theory (MP2) and a relativistic effective core potential. Applying a scaled quantum mechanical (SQM) method the complete (and up to now the best) force field of the molecule has been evaluated. Based on that SQM force field the complete assignment of the vibrational spectra of TeCl ₄ has been performed. The electron diffraction analysis resulted in the following geometrical parameters: r _a (Te–Cl _ax ) = 243.5(5), r _a (Te–Cl _eq ) = 229.4 (5) pm, Cl _ax –Te–Cl _ax = 176.4(6), Cl _eq –Te–Cl _eq = 103.7(7)°. The molecular geometry is consistent with valence shell electron pair repulsion theory. Comparison with the respective parameters of Te(CH ₃ ) ₄ supports a previous bonding model for these compounds. Both the computations and the experimental data indicate a much less flexible structure for TeCl ₄ than was found for Te(CH ₃ ) ₄ .