Synthesis and absolute structure of (R)-2-(benzyl-selan-yl)-1-phenyl-ethanaminium hydrogen sulfate monohydrate:...

A hydrogen sulfate salt, C₁₅H₁₈NSe⁺·HSO₄ ^-·H₂O or [BnSeCH₂CH(Ph)NH₃ ⁺](HSO₄ ^-), of a chiral selenated amine (R)-2-(benzyl-selan-yl)-1-phenyl-ethan-amine (BnSeCH₂CH(Ph)NH₂) has been synthesized and characterized by elemental analysis,¹H and ¹³C{¹H} NMR, FT-IR analysis, and single-crystal X-ray diffraction studies. The title salt crystallizes in the monohydrate form in the non-centrosymmetric monoclinic P2₁ space group. The cation is somewhat W shaped with the dihedral angle between the two aromatic rings being 60.9 (4)°. The carbon atom attached to the amine nitro-gen atom is chiral and in the R configuration, and, the -C-C- bond of the -CH₂-CH- fragment has a staggered conformation. In the crystal structure, two HSO₄ ^- anions and two water mol-ecules form an R ⁴ ₄(12) tetra-meric type of assembly comprised of alternating HSO₄ ^- anions and water mol-ecules via discrete D(2) O-H⋯O hydrogen bonds. This tetra-meric assembly aggregates along the b-axis direction as an infinite one-dimensional tape. Adjacent tapes are inter-connected via discrete D(2) N-H⋯O hydrogen bonds between the three amino hydrogen atoms of the cation sandwiched between the two tapes and the three HSO₄ ^- anions of the nearest asymmetric units, resulting in a complex two-dimensional sheet along the ab plane. The pendant arrangement of the cations is stabilized by C-H⋯π inter-actions between adjacent cations running as chains down the [010] axis. Secondary Se⋯O [3.1474 (4) Å] inter-actions are also observed in the crystal structure. A Hirshfeld surface analysis, including d _norm, shape-index and fingerprint plots of the cation, anion and solvent mol-ecule, was carried out to confirm the presence of various inter-actions in the crystal structure.