Theoretical Studies of Group 1 Metal Complexes with Hydrogen Fluoride,M(HF)_n,M = Li, Na,and K:A New Type of Electrides

摘要

Small clusters of group 1 metal complexes with hydrogen fluoride molecules M(HF)_n,M = Li,Na,and K,are studied with the ab initio molecular orbital method.The trimer M(HF)_3 forms a C_(3v)cluster,in which the metal atom is ionized and the ejected electron is trapped on the top of three equivalent HF molecules.The optimized geometric structure of Li(HF)_3 is almost identical with that of the ion pair Li~+(HF)_3Cl~-by replacing a Cl~-anion with an ejected electron {e~-};thus Li(HF)_3 can be described as Li~+(HF)_3{e~-}.The entity {e~-} is trapped under the electrostatic field created by three HF bond dipoles;and at the same time,the HF bonds are polarized and weakened.A triplet anion {e~-}(HF)_3Li~+(HF)_3{e~-} is stable and is a possible anion unit of electrides.