[Co(TMSA)2(DMAPY)], pointed away from the Co(II) ion which was only coordinated by the pyridine nitrogen atom (Figure ). While it likely was the rigidity of the DMAPY ligand paired with localized electron-richness of the pyridine nitrogen that prevented a chelating bonding mode of the Lewis base in 4, we attributed the three-fold coordination seen in 3 to the considerable special demand of the tert-butyl side chains. These may tolerate the coordination of only one imine nitrogen to the Co(II) ion at a time. As it can be seen from 5 is reproduced from the data provided by Müller and co-workers. It is a consequence of a preferential tilt of the DMAPY ligand towards one of the TMSA ligands.