STRUCTURE OF ALKALI HYDROXIDES .V. INFRARED SPECTRA OF MATRIX-ISOLATED RBOH, RBOD, NAOH, AND NAOD

The infrared spectra of matrix-isolated RbOH, RbOD, NaOH, and NaOD have been observed. Both the alkali-metal-oxygen stretch v1 and the bending mode v2 have been assigned for each species. The metaloxygen stretching mode is found at 354.4, 345, 431, and 422 cm-1 for RbOH, RbOD, NaOH, and NaOD, respectively; the bending mode v2 is observed at 309.0, 229, 337, and 250 cm-1, respectively. Combination of the results of this study with the microwave measurements for RbOH and RbOD indicates an essentially linear structure for these species. The isotope shift for n observed in NaOH coupled with reasonable bond lengths indicates an equilibrium configuration of NaOH which probably does not deviate significantly from linearity. The assumption of a linear model with a harmonic bending potential yields force constants of 0.046×10-18 and 0.053×10-18 Nm (0.046 and 0.053 mdyn ° Å) for RbOH and NaOH, respectively. These results are consistent with our previously reported results for CsOH.