Comment 2,2'-Bi-2-imidazoline is a versatile ligand for transition metals; it has the potential to act as a bidentate a,- diimine, a diamine or, if deprotonated, as a dianionic bridge between two metal ions. The infrared spectrum of the compound shows some unusual features; the imine stretching frequency (UC~N, 1571 cm-1) is very low, much closer to that expected for a complex with a metal ion bound to the imine than for the free imine. In comparison, the equivalent ...
