Structure Analysis and Hydrogen Bond Character of K₃H(SO₄)₂

Abstract

Structure analysis of K₃H(SO₄)₂ was performed by X-ray diffraction experiments in order to study the hydrogen bond character in connection with the geometrical isotope effect. Crystal data at room temperature were obtained as a=9.777(1)Å, b=5.674(1)Å, c=14.667(4)Å, β=102.97(2)° and the space group A2⁄a, Z=4. The hydrogen bond length R_OO determined from the positional parameters was 2.493(1)Å which was close to but still longer than the so called critical bond length r_c. The electron density of split hydrogen atoms was observed on a differential Fourier map. It is concluded that the hydrogen atoms take the disordered state at room temperature and the distance between hydrogen atoms R_HH is approximately 0.65 Å. The possibilities for the existence both of the low temperature phase and the high temperature prototype phase are discussed.