THEORETICAL-STUDIES OF FLUOROCARBONS .2. FLUORINE AND CHLORINE SUBSTITUTED ALKANES

Ab initio SCF and semi-empirical geometry optimizations are carried out for fluoromethanes and chloromethanes, for fluorochloromethanes, and for fluorine or chlorine substituted ethane. We also examine the charge distributions inferred from Mulliken population analyses. In order to establish a reliable foundation for calculations on systems such as these, we discuss in detail the effects of using different s/p basis sets and of including polarization functions on different centres. We find significant differences between fluorine and chlorine substituted alkanes. Apparent correlations between the Mulliken charge on carbon and the reaction enthalpy for hydrogen-atom abstraction by chlorine atoms are noted for F and Cl substituted methane. © 1990.