THE SYNTHESIS OF SOME LIPOPHILIC TETRADENTATE LIGANDS FOR USE IN THE FORMATION OF METAL-LINKED POLYMERS

Two lipophilic tetradentate ligands, 5,5'-di-t-butyl- and 5,5'-dihexyl -2,2'-bipyrimidine, were prepared via either Ullmann or nickel(0)-prom oted reactions in low but useful yields. Approaches towards the synthe sis 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'-te tra(octyloxy)-2,2'-bibenzimidazole (from NN'-bis[4,5-di(octyloxy)-2-ni trophenyl]oxamide), were uniformly unsuccessful for preparing the 2,2' -biheteroaryl compounds.