Crystal structures of bis­­[(9S,13S,14S)-3-meth­­oxy-17-methyl­morphinanium] tetra­chlorido­cobaltate and tetra­chlorido­cuprate

(9S,13S,14S)-3-Meth­oxy-17-methyl­morphinan (dextromethorphan) forms two isostructural salts with (a) tetra­chlorido­cobaltate, namely bis­[(9S,13S,14S)-3-meth­oxy-17-methyl­morphinanium] tetra­chlorido­cobaltate, (C18H26NO)2[CoCl4], and (b) tetra­chlorido­cuprate, namely bis­[(9S,13S,14S)-3-meth­oxy-17-methyl­morphinanium] tetra­chlorido­cuprate, (C18H26NO)2[CuCl4]. The distorted tetra­hedral anions are located on twofold rotational axes. The dextromethorphan cation can be described as being composed of two ring systems, a tetra­hydro­naphthalene system A+B and a deca­hydro­isoquinolinium subunit C+D, that are nearly perpendicular to one another: the angle between mean planes of the A+B and C+D moieties is 78.8 (1)° for (a) and 79.0 (1)° for (b). Two symmetry-related cations of protonated dextromethorphan are connected to the tetra­chlorido­cobaltate (or tetra­chlorido­cuprate) anions via strong N—H⋯Cl hydrogen bonds, forming neutral ion associates. These associates are packed in the (001) plane with no strong attractive bonding between them. Both compounds are attractive crystalline forms for unambiguous identification of the dextromethorphan and, presumably, of its optical isomer, levomethorphan.