Scheme 1. Synthetic schemes for the preparation of tris(4,4′-di-tert-butyl-2,2′-bipyridine)cobalt(ii) and tris(4,4′-di-methoxy-2,2′-bipyridine)cobalt(ii) complexes. Three equivalents of each indicated bipyridine ligand was reacted with one equivalent of cobalt chloride hexahydrate in methanol at 55 °C for approximately 3 h. The resulting solution containing the Co(bpy-R₂)₃Cl₂ complex was split into two round-bottom flasks and the corresponding counteranions were introduced. Ten equivalents of tetrabutylammoniumhexafluorophosphate (TBAPF₆) or lithium perchlorate (LiClO₄) were added to the designated flask. The resulting solid was isolated via vacuum filtration and washed with cold methanol followed by cold ethyl ether. To obtain the chloride salt, the original reaction was evaporated under reduced pressure and resulting solid washed with cold ethyl ether.