Enantiopure terdentate N-donor ligands and their Fe(II) and Co(II) complexes

A series of Fe(II) and Co(II) complexes with two chiral terpy ligands (L2, L3, L4 and L5) and a related pyridine-diimine (L6) have been prepared and structurally characterized. In all cases except one, the metals are five coordinated with an approximately trigonal-bipyramidal coordination sphere. The two lateral N-donor atoms occupy the apical positions. The only exception is complex 5 (CoL4Cl2), where one lateral N-donor interacts only weakly with the metal (2.63 vs. 2.21 Å) forming thus a nearly tetrahedral coordination sphere. L4 and L6 were also structurally characterized. They show the expected transoid arrangement of the donor atoms.