MOLECULAR AND CRYSTAL-STRUCTURE OF 6-METHYLSPARTEINE DIPERCHLORATE

The crystal structure determined by X-rays and the C-13-NMR spectra of 6-methylsparteine diperchlorate, [C16H30N2]2+ *2ClO4-, are presented. The title compound was obtained by chemical transformations of sparteine. The crystals are monoclinic, P2(1), the final R being 0.075 for 1441 independent reflections. The quinolizidine moieties (piperidine-rings systems A/B and C/D) are both preset in the trans configuration; the piperidine rings A, B, C and D have a chair, chair, boat, and chair conformation, respectively. C-13-NMR spectra revealed the same conformation in DMSO-H-2(6)-solution as in the crystal. The two protonated nitrogen atoms are each hydrogen-bonded to a different perchlorate anion: N(1)...O(2) is 3.003(11) and N(16)...O(8) is 2.940(14) angstrom. The two perchlorate anions show a strong orientational disorder; similarly large vibrational parameters are observed for the terminal atoms of the cation and for the atoms in flexible quinolizidine moiety C/D.