Preparation and Characterization of Oxalyl Dicyanide.

Oxalyl dicyanide and its 1,4-dioxane adduct were obtained as colorless crystalline solids from the reaction of oxalyl chloride with trimethylsilyl cyanide. Their crystal structures and vibrational spectra, supported by quantum chemical calculations, are presented. In the solid state, oxalyl dicyanide adopts C2h symmetry with the preferred trans-anti configuration. The 13C NMR spectrum shows two distinct resonances at 159.8 and 109.9 ppm, while characteristic ν(C≡N) and ν(C═O) stretching vibrations are observed at 2243 and 1734 cm-1, respectively. Hydrolysis proceeds rapidly to oxalic acid and hydrogen cyanide, with transient formation of the unusual tetraol 2,2,3,3-tetrahydroxysuccinonitrile, as confirmed by single-crystal X-ray diffraction.