Vibrational spectra and conformational analysis of chloromethylfluoroformate

Abstract

Infrared spectra (4000-50 cm −1) of FCOOCH 2Cl, FCOOCD 2Cl and FCOOCDHCl in the vapour and solid phases and Raman spectra (3500-50 cm −1) of these compounds in the vapour, liquid and solid phases are reported and an assignment is proposed. The spectra indicate that in each aggregation state one single conformer is present. The simulation of the i.r. vapour phase contours indicate that, at least in the vapour phase, this is the ( s- cis, gauche) conformer. In the vapour phase for the near and mid i.r. and the Raman spectra of the partially deuterated derivative, the bands due to the stretching vibrations of the antiperiplanar and synclinal CH bonds of this gauche conformer are observed. The remaining single isolated CH band in the spectra of solid FCOOCDHCl indicates that a conformational change into a trans conformer takes place upon crystallization of the product. Finally, a normal coordinate analysis, based upon a transferable simplified valence force field, is carried out.