Knowledge Bank

Normal coordinate treatment for the series $CH2XY$ halogenated methanes $(X=ForI,Y=ClorBr)$ was carried out using a 709 digital computer. The most general quadratic, valence force, potential function was assumed. A reasonable set of 34 force constants was obtained for each member, that reproduced exactly the observed frequencies using a peturbation method. These calculations favor the assignments for the fundamentals of these molecules as given by Pitzer and Gelles. These fundamentals are (in $cm-1)$: [FIGURE] The following mean square amplitudes of vibration at $298.16\circ K$ were obtained (in $10-3A2$):[FIGURE] Coriolis coupling coefficients as well as thermodynamic properties are being calculated and will be reported.