4-Vinyl-, 6-vinyl-, and 4'-vinyl-2,2':6',2"-terpyridinyl ligands: their synthesis and the electrochemistry of their transition-metal coordination complexes

TLDR: The 4'-Vinyl-2,2':6',2''-terpyridinyl was readily electropolymerizable simple and mixed-ligand complex monomers with cobalt, ruthenium and iron with polymerization rates whose magnitude varied with position and number of vinyl substituents.

Abstract: 4'-Vinyl-2,2':6',2''-terpyridinyl was conveniently prepared from 2-acetylpyridine via -oxoketene dithioacetal methodology, the intermediate 4'-(methylthio)-2,2':6',2''-terpyridinyl being converted into the corresponding 4'-methyl derivative with methylmagnesium bromide and bis(triphenylphosphino)nickel(II) dichloride followed by generation of the methyl anion with lithium tetramethylpiperidide, reaction of the anion with chloromethyl methyl ether, and introduction of the vinyl group by treatment of the ether with potassium tert-butoxide/THF. Analogous reactions led to the 4-vinyl- and 6-vinyl isomers by using the appropriate methyl-substituted 2-acetylpyridine except that in these instances desulfurization of the 4'-methylthio group with nickel boride was an addition step. These vinyl-substituted ligands formed a variety of readily electropolymerizable simple and mixed-ligand complex monomers with cobalt, ruthenium, and iron with polymerization rates whose magnitude varied with position and number of vinyl substituents.