Knowledge Bank

Potential constants for $CH3Br,CD3Br,CH2Br,CD2Br2,CHDBr2,CHD2Br,CH2DBr,CHBrF2,CDBrF2,CHBrCl2,CDBrCl2$, and $CHFBr2$ have been determined using the Wilson FG matrix method. With the exception of a few cases, the constants are in good agreement with those obtained in previous investigations in this laboratory for other halogenated methanes. No experimental values of the fundamentals for the $CHDBr2,CHD2Br,CH2DBr$, and $CDBrF2$ molecules could be found in the literature, but for the other molecules the agreement between the calculated and observed values of the fundamentals, in general, was within 2 percent. Tetra-hedral angles were assumed in all cases and a quadratic potential function containing all possible second-degree terms was used. The calculations also made it possible to trace the behavior of characteristic frequencies in going from one molecule to another having bonds in common. Finally, thermodynamic functions were calculated for all 12 molecules.