Infrared spectra of eighteen halogen-substituted methanes

Abstract

In order to s t ud y how the vibratio nal freq uenci es of methane vary with haloge n sub-stit utions, the infrared spectra of the following halo g~n-s ub stit u te d methanes. have been st udied with a prism spectrometer between 2 and 38 mICrons: Carbon tetraflu onde, chloro-t rifiuoromethan e dichlorodifiuoromethane trichlorofiuorom ethane, car bo n tet rach lorid e, trichlorobromom~than e, dichlorodibromol~ethane , fiuoroform, di~uoroch l o romet h an e, di-chlorofluoromethane chloroform di chlorobromomethane, chlorodlbromomethalle , bromo-form , iodoform, me th ylene flu orid e, methylene. chloride, and m ~th~ l ene iodide. Spectra are prese nted as obtained at room temperature ll1 t he vapor and lIquid states, an d l.n a f ew cases in sol ut ion. The bands are interpreted as fundam entals, overtones, combmatlO n, and differe nce bands. Tables and grap hs display t he regularities existing among t he various fundam entals of these molecules and other haloge n-subst ituted methanes. Force-constant calculat ions, using an approximate potential function with ge neral constants transferred from one molec ul e to another a re reported.