The infrared fundamental intensities and polar tensor of CF 4

Abstract

Atomic polar tensors of carbon tetrafluoride are calculated from experimental fundamental infrared intensities measured by several research groups. Quantum chemical calculations using a 6-311++G(3d, 3p) basis set at the Hartree-Fock, Möller-Plesset 2 and Density Functional Theory (B3LYP) levels are used to resolve the sign ambiguities of the dipole moment derivatives. The resulting carbon mean dipole moment derivative, p ̄ C =2.051 e, is in excellent agreement with values estimated by a MP2/6-311++G(3d, 3p) theoretical calculation, 2.040 e, and by an empirical electronegativity model, 2.016 e. The p ̄ C value determined here is also in excellent agreement with the one obtained from the CF 4 1s carbon ionization energy using a simple potential model, 2.059 e. Crawford's G intensity sum rule applied to the fundamental intensities of CH 4, CH 3F, CH 2F 2 and CHF 3 results in a prediction of a 1249 km mol −1 intensity sum for CF 4 in good agreement with the experimental values of 1328±37.9, 1208.0±54.4 and 1194.8±7.4 km mol −1 reported in the literature.