Understanding the microcrystal tests of three related phenethyl­amines: the ortho-metallated (±)-amphetamine formed with gold(III) chloride, and the tetra­chloridoaurate(III) salts of (+)-methamphetamine and (±)-ephedrine

The ortho-metallation product of the reaction of (±)-amphetamine with gold(III) chloride, [D,L-2-(2-amino­prop­yl)phenyl-κ²N,C¹]dichlorido­gold(III), [Au(C₉H₁₂N)Cl₂], and the two salts resulting from crystallization of (+)-methamphetamine with gold(III) chloride, D-meth­yl(1-phenyl­propan-2-yl)aza­nium tetra­chlorido­aurate(III), (C₁₀H₁₆N)[AuCl₄], and of (±)-ephedrine with gold(III) chloride, D,L-(1-hy­droxy-1-phenyl­propan-2-yl)(methyl)aza­nium tetra­chlorido­aurate(III), (C₁₀H₁₆NO)[AuCl₄], have different structures. The first makes a bidentate complex directly with a dichloridogold(III) group, forming a six-membered ring structure; the second and third each form a salt with [AuCl₄]⁻ (each has two formula units in the asymmetric unit). The organic components are all members of the same class of stimulants that are prevalent in illicit drug use. These structures are important contributions to the understanding of the microcrystal tests for these drugs that have been employed for well over 100 years.