Molecular and crystal structure of bis-quinolizidine immonium salts, II: Δ₁₍₆₎-dehydrosparteinium monoperchlorate

Abstract

Δ₁₍₆₎-Dehydrosparteinium monoperchlorate, [C₁₅H₂₅N₂]⁺·ClO ⁻₄ , is orthorhombic∶P2₁2₁2₁,a=12.473(2),b=24.292(3),c=10.835(1) Å,V _c =3353.7(9) ų,Z=8,D _x =1.32,D _m =1.32 g cm⁻³, μ(CuKα)=20.7 cm⁻¹. The finalR was 0.097 for 2091 observed counter reflections. A partial disorder of the crystal structure has been observed. The two independent perchlorate anions are orientationally disordered, and the peripheral atoms in the cation skeletons have large temperature factors due both to conformational disorder of ringsA and to disordered orientations of the whole cations alike. In ringsA, atoms C(3) and C(4), trans-annular to the immonium bond, are disordered to a different extent in each of the two independent cations. RingsB,C, andD have sofa (distorted towards half-chair), chair, and chair conformations, respectively. The quinolizidinium and quinolizidine moieties have planar and cis configurations, respectively. The title compound was obtained from Δ⁵-dehydrosparteine, the product of mercuric acetate dehydrogenation of sparteine at room temperature. From¹³C NMR measurements in²H₂O and in DMSO-²H₆ it is evident that, in solution, the molecular geometry with chair/chair cis-ring fusion within the quinolizidine moiety is present, as was found in the crystalline state by X-ray analysis.