A Dimer of Hydrogen Cyanide Stabilized by a Lewis Acid

Abstract

Abstract A highly labile dimer of hydrogen cyanide, HCN⋅⋅⋅HCN, was extracted from liquid HCN by adduct formation with the bulky Lewis acid B(C 6 F 5 ) 3 , affording HCN⋅⋅⋅HCN−B(C 6 F 5 ) 3 , which was fully characterized. The influence of the solvent (HCN, CH 2 Cl 2 , and aromatic hydrocarbons) on the crystallization process was studied, revealing dimer formation when using HCN or CH 2 Cl 2 as solvent, whereas aromatic hydrocarbons led to the formation of monomeric arene⋅⋅HCN−B(C 6 F 5 ) 3 adducts, additionally stabilized by η 6 ‐coordination of the aromatic ring system similar to well‐known half‐sandwich complexes.