Sarcosine sarcosinium chloride and sarcosine sarcosinium bromide

► Structures of the sarcosine salts with dimeric cations 2Sar·HCl and 2Sar·HBr were determined. ► Both crystals are isotypic and crystallize in the orthorhombic system (polar Pca21 space group). ► Vibrational spectra of 2Sar·HCl, 2Sar·HBr as well as Sar·HCl and Sar·HBr are shown. ► The presence of short O⋯O hydrogen bonds is reflected in the IR spectra of 2Sar·HCl, 2Sar·HBr. The crystal and molecular structures and vibrational spectra of sarcosine sarcosinium chloride (I) and sarcosine sarcosinium bromide (II) have been determined and are discussed. In the case of sarcosine sarcosinium bromide (II), an old publication exists, where the structure is reported, but the data given are less accurate and hydrogen positions have not been determined at all. Both salts are isotypic and crystallize in the orthorhombic system (space group Pca21), the asymmetric unit contains two formula units. The O⋯O distances in dimeric cations are equal to 2.469(2)Å and 2.463(2)Å in (I) and 2.453(3)Å and 2.464(3)Å in (II). The presence of these short hydrogen bonds is reflected in the infrared spectra. The vibrational spectra of sarcosinium chloride and sarcosinium bromide are shown for comparison.