The Synthesis of Some Lipophilic Tetradentate Ligands for Use in the Formation of Metal-Linked Polymers

Abstract

Two lipophilic tetradentate ligands, 5,5′-di-t-butyl- and 5,5′-dihexyl-2,2′-bipyrimidine, were prepared via either Ullmann or nickel(0)-promoted reactions in low but useful yields. Approaches towards the synthesis of lipophilic ligands based on 2,2′-biimidazole, namely 4,4′,5,5′-tetrabutyl-2,2′-biimidazole (from decane-4,5-dione) and various 4,4′,5,5′-tetra( arylamino )- 2,2′-biimidazoles (from 4,4′,5,5′-tetrabromo-2,2′-biimidazole and arylamines), and a 2,2′- bibenzimidazole , 5,5′,6,6?-tetra( octyloxy )-2,2′-bibenzimidazole (from N,N′- bis [4,5-di( octyloxy )-2-nitrophenyl] oxamide ), were uniformly unsuccessful for preparing the 2,2′-biheteroaryl compounds.