Crystal structures and Hirshfeld surface analyses of ,-di-methyl-acetamide-1-(dimethyl-λ-aza-nyl-idene)ethan-1-ol tribromide (1/1), ,-di-methyl-acetamide-1-(dimethyl-λ-aza-nyl-idene)ethan-1-ol di-bromido-iodate (1/1) and ,-di-methyl-acetamide-1-(dimethyl-λ-aza-nyl-idene)ethan-1-ol di-chlorido-iodate (1/1).

In the title compounds, ,-di-methyl-acetamide-1-(dimethyl-λ-aza-nyl-idene)ethan-1-ol tribromide (1/1), CHNO·CHNO·Br or (CHNO)·(CHNO), (), ,-di-methyl-acetamide-1-(dimethyl-λ-aza-nyl-idene)ethan-1-ol di-bromido-iodate (1/1), CHNO·CHNO·BrI or (CHNO)·(CHNO), (), and ,-di-methyl-acetamide-1-(dimethyl-λ-aza-nyl-idene)ethan-1-ol di-chlorido-iodate (1/1), CHNO·CHNO·ClI or [(CHNO)·(CHNO)]·(ClI), (), all the anions are almost linear in geometry and all the cations, except for the methyl H atoms, are essentially planar. In the crystal structure of (), the cations are linked by pairs of C-H⋯O hydrogen bonds, forming inversion dimers with an (8) ring motif. These dimers also exhibit O-H⋯O hydrogen bonding. Dimerized cation pairs and anions are arranged in columns along the axis. In the crystal of (), the cations are linked by pairs of O-H⋯O and C-H⋯O hydrogen bonds, forming an (14) ring motif. These groups of cations and the anions form individual columns along the axis and jointly reside in planes roughly parallel to (011). In the crystal of (), cations and anions also form columns parallel to the axis, resulting in layers parallel to the (020) plane. Furthermore, the crystal structures of (), () and ( are consolidated by strong halogen (Br and/or I and/or Cl)⋯H and weak van der Waals inter-actions. In addition to the structural evaluation, a Hirshfeld surface analysis was carried out.