Mixed salts of amino acids: l-lysinium(2+) chloride nitrate, l-lysinium(2+) chloride tetrafluoroborate and l-lysinium(2+) chloride perchlorate

The mixed salts of l-lysinium(2+) chloride nitrate (I), l-lysinium(2+) chloride tetrafluoroborate (II) and l-lysinium(2+) chloride perchlorate (III) have been obtained from aqueous solution and their crystal structures have been determined. All three crystals crystallize in the monoclinic system (space group P21), (II) and (III) are even isostructural. The asymmetric unit of (I) contains one formula unit (l-Lys2+·Cl−· NO 3 - ), in contrast to the asymmetric units of (II) and (III) which contain two formula units of (l-Lys2+·Cl−· BF 4 - ) and (l-Lys2+·Cl−· ClO 4 - ). The l-Lys2+ cations in the structures have similarly extended conformation, although there is a difference: In (I), the α-carbon is in gauche and the NH3-group in trans position, in (II) and (III) it is the other way round. The crystals are stabilized by an extensive network of OH···Cl, NH···Cl, and NH···O, NH···F hydrogen bonds. ATR FTIR and Raman spectra of the salts have been registered and are discussed.