Spectroscopy and structure of sparteine and 2-methylsparteine dichloride metal complexes

Copper, cobalt, nickel and zinc chloride complexes with sparteine and 2-methylsparteine were synthesised. The 1:1 metal:sparteine stoichiometry was confirmed by elemental analysis and mass spectra. Absorption spectra of the solids were studied in the IR, and their diffuse-reflectance spectra in the UV–Vis and the NIR spectral range. The spectra obtained are similar to previous results obtained in solutions, suggesting that the metal ion coordination sphere in solution remains the same as in the crystal lattice, with the sparteine and 2-methylsparteine assuming the folded all-chair conformation with trans A–B and cis C–D rings and both nitrogen atoms coordinated with the metal. The structure was confirmed by NMR and X-ray diffraction data, and compared to that of other similar complexes. q 2004 Elsevier B.V. All rights reserved.