Trimethylsilyl trichloroacetate vibrational, structural and electronic properties and their comparison with related acetates

The molecular structure of trimethylsilyl trichloroacetate, CCl3C(O)OSi(CH3)3, was determined by ab initio (MP2) and DFT calculations using 6-31G(d), 6-311G(d,p), 6-311++G(d,p) and 6-311++G(3df,3pd) basis sets. The infrared and Raman spectra for the liquid phase were also recorded and the bands observed assigned to the vibrational normal modes. The study was completed using natural bond orbital (NBO) analysis and atoms in molecules (AIM) calculations. The comparison between the calculated molecular geometrical parameters, conformation and vibrational properties and those measured for CX3C(O)OR [X = F, Cl and R = CH3, Si(CH3)3] was of particular interest in order to check the behavior of the CO and CO with respect to the different substitutions. The experimental vibrational data, along with calculated theoretical force constants, were used to define a scaled quantum mechanical force field for the target system that enabled us to estimate the measured wavenumbers with a final root-mean-square deviation of 8.92 cm−1.

► Theoretical data indicate that there is only one conformer with Cs symmetry. ► Trimethylsilyl trichloroacetate is a convenient reagent for the silylation of phenols. ► The spectral features were subsequently assigned to the different normal modes of vibration. ► The lone pairs of Cl and F atoms and their interaction on the σ* CC and σ* CO. ► The rotation barrier, COCC dihedral angle is the same for the CX3C(O)OSi(CH3)3 (X = CL, F).