On the structure of liquid hydrogen fluoride.

Abstract

The liquid state is the most complex phase of matter. Densities of liquids are comparable to densities of the solids, implying that the forces between particles in the liquid are of the same magnitude as those forces present in the solid. However, there is no simplification due to the presence of a lattice and no satisfactory analytic theory of the liquid state exists. However, despite this complexity, the liquid state is an outstandingly important chemical milieu in which many reactions take place. Strongly associated fluids are particularly complex and the structure and properties of these fluids provide an exacting and stringent test of theory. Here, we report the first investigation of the structure of hydrogen fluoride at the level of the distributions of pairwise interatomic distances, the partial pair correlation functions. Liquid HFis an important chemical and it is widely used in the petrochemical industry, as a catalyst for hydrocarbon management, and in the glass and ceramics industries. [1, 2] Academically, its superior properties as a solvent have found application in both organic and inorganic chemistry, and the superacidic properties have been exploited in both disciplines, in the study of reactive intermediates and reaction mechanisms [3, 4] That these highly desirable properties are not more widely applied is mainly due to the exceedingly toxic and corrosive nature of the material, [5] which is severe when anhydrous and only somewhat lessened in solution. Indeed, given the properties of liquid HF, it has been stated that the calculation of its properties is to be preferred over measurement. [6] The true importance of this fluid does not solely rest with its industrial and academic applications; it is the simplest archetype for the strong hydrogen bond, and the molecular