Iodides of sarcosine

► Crystals Sar·HI and 2Sar·HI are obtained and characterized structurally and by IR, Raman spectra. ► 2Sar·HI is a new salt with dimeric Sar⋯Sar+ cation and 2.496(4) Å O⋯O distance. ► Sar·HI (space group P21) is isotypic with Sar·HCl and Sar·HBr. ► 2Sar·HI (space group P21/c) is not isostructural with 2Sar·HCl and 2Sar·HBr (space group Pac21). Two crystalline salts Sar·HI and 2Sar·HI are obtained in result of investigation of the system sarcosine+HI+H2O. The crystal and molecular structures as well as vibrational spectra of Sar·HI (Sar+·I−) and 2Sar·HI ((Sar⋯Sar+)·I−) have been determined and are discussed. Sar·HI is isotypic with Sar·HCl and Sar·HBr (space group P21). In contrast, 2Sar·HI represents a new structure with an A⋯A+ type dimeric cation (space group P21/c), i.e., it is not isostructural with the isotypic pair of 2Sar·HCl and 2Sar·HBr (space group Pac21). The asymmetric units of both species contain one formula unit each. The O⋯O distance in the dimeric Sar⋯Sar+ cation is equal to 2.496(4) Å. The presence of this short hydrogen bond is reflected in the infrared spectrum.