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

Abstract

(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.

Keywords

• crystal structure
• dextromethorphan
• tetrachloridocobaltate
• tetrachloridocuprate
• N—H...Cl hydrogen bonds