An Ab initio molecular orbital study of the systematics in the photoelectron spectra of halomethanes

Ab initio molecular orbital calculations on fluoro- and chloro-methanes, CH4—n X n , predict the correct trends in the photoelectron spectra except in the case of the C(2s) bands of fluoromethanes. Thus, the calculated energies corresponding to the lone pair, σ (CX) and C(1s) bands increase with increasing n as found experimentally; the C(2s) energy in chloromethanes decreases with increasing n, again, in agreement with experiment.