Investigations on the Amidine System in Amidinobenzisothiazole Derivatives

Abstract The amino/imino equilibrium is studied in free bases and hydrochloride salts of amidinobenzisothiazole derivatives by IR and 1 H‐NMR spectroscopy. The X‐ray crystallographic analysis of two of these compounds shows that the free base exists as amino form whereas the hydrochloride as imino form.