An electron-diffraction investigation of gaseous perchloric acid and calculation of its skeletal force field and amplitudes of vibration

Abstract

The electron-diffraction pattern from gaseous perchloric acid at 35° has been recorded over the range s= 0·74 to 34·70 Å^–1. Least-squares refinements assuming spectroscopic values for the amplitudes of vibration lead to two possible sets of structural parameters. These are (a)r_g(1) for Cl–O 1·408 Å, r_g(1) for Cl–OH 1·635 Å, ∠O–Cl–O 112·8°, and (b)r_g(1) for Cl–O 1·410 Å, r_g(1) for Cl–OH 1·646 Å, ∠ O–Cl–O 117·3°. For both sets of results the estimated standard deviations are 0·002, 0·007, and 0·5°. A significance test and other evidence suggest a preference for structure (a).