The structure of tris(chloromethyl)amine in the gas phase using quantum chemical calculations and gas electron diffraction and as a solid and melt using Raman spectroscopy

Abstract

The equilibrium structure of tris(chloromethyl)amine, N(CH2Cl)3, has been determined in the gas phase using electron diffraction. Single-step distance corrections (representing the differences between the interatomic distances from the equilibrium structure and those from the vibrationally averaged structure) and amplitudes of vibration have been computed using semi-empirical molecular dynamics (SE-MD) simulations in order to treat accurately the description of the low-frequency, large-amplitude vibrational modes associated particularly with one CH2Cl group. A series of complementary theoretical calculations using the SOGGA11-X DFT functional with correlation-consistent basis sets of double-, triple-, and quadruple-ζ quality is also presented. The agreement between the experimental and theoretical equilibrium structural parameters attests to the accuracy of the applied theoretical calculations and of our gas-phase structural solution. Raman spectra have been recorded over a range of temperatures, allowing the solid and the melt to be studied, and the Raman-active intramolecular modes to be identified. Free from the influence of intermolecular interaction, the structure of tris(chloromethyl)amine in the gas phase is markedly different to that reported in the literature for the single crystal. This is discussed, and evidence for the anomeric effect in tris(chloromethyl)amine is evaluated.