Vibrational intensities of F2CS and Cl2CS

摘要

The CNDO approximate molecular wavefunctions for F2CS and Cl2CS have been applied to the calculation of the derivatives of the dipole moment with respect to the symmetry coordinates. Unique sets of experimental derivatives in theA1symmetry species of these molecules are definitely preferred according to these calculations. Two experimental sets of derivatives in theB1symmetry species of each molecule are consistent with the calculated results. All the preferred experimental derivatives for the stretching coordinates,part; psol;part; rCFandpart; psol;part; rCCl, and the inhyphen;plane bending coordinate,part; psol;part;agr;, have negative signs. The CF outhyphen;ofhyphen;plane bending derivative in F2CS appears to be negative although the corresponding CCl derivative is probably positive. The theory qualitatively reflects trends in the magnitudes of these derivatives in the different X2CY molecules and in different symmetry species of the same molecule. Empirical equations of the typelpar;part; psol;part; rCClrpar;Cl2CSminus;lpar;part; psol;part; rCFrpar;F2CSequals;lpar;part; psol;part; rCClrpar;Cl2COminus;lpar;part; psol;part; rCFrpar;F2CO, relating corresponding derivatives for F2CO, Cl2CO, F2CS, and Cl2CS, are discussed.