Synthesis and crystal structures of iron(II) dichloride complexes with α-isosparteine, β-isosparteine and 2-methylsparteine

Tetrahedrally distorted complexes of α-isosparteine, β-isosparteine and 2-methylsparteine with FeCl2 have been synthesised. Crystal structures of these complexes are reported and compared with the structure of (−)-sparteine analogue. Coordination to Fe(II) center in β-isosparteine and 2-methylsparteine brings about an inversion at the N16 nitrogen and change in configuration at the ring junction from trans to cis, accompanied by a change in the C-ring conformation from boat to chair. The all-chair α-isosparteine skeleton remains unchanged upon complexation. Structural parameters of the complexes are investigated using Becke three-parameter hybrid exchange functional combined with the Lee–Yang–Parr correlation functional (B3LYP) with 6-31G and 6-311G basis sets applied for geometry optimizations.