Boron trichloride and the N-substituted benzimidoyl chlorides PhCCl: NR (R= Me, Et, or Ph) form 1: 1 adducts which are formulated as nitrilium tetrachloroborates PhCNR+ BCl4–on the basis of their infrared spectra, which have ν (CN) at 2380, 2365, and 2318 cm.–1, respectively. Alkaline hydrolysis of these hydroscopic solid tetrachloroborates gives chloride, borate, and the amide PhCONHR. The alkyl compounds decompose at 150° to ...