Crystal structure of pseudokopsinine and its salts

The X-ray diffraction study of an indoline alkaloid, pseudokopsinine, extracted from the plant Vinca erecta and its mono- and double salts is performed. The experimentally determined positions of Н atoms suggest the sp 3 hybridization of the indoline nitrogen atom in the base and salts. The pseudokopsinine base and double salt have an intramolecular Н bond between the NH group proton and the ether oxygen atom of the methoxycarbonyl group, which is absent in the monosalt and the related indolines. The intermolecular Н bonds and/or the packing efficiency cause a conformational change in F and Е heterocycles in the indoline hetero framework of pseudokopsinine salts in comparison with that observed in the base.