Terpyridine- and bipyridine-based ruthenium complexes as catalysts for the Belousov-Zhabotinsky reaction.

We report the successful use of Ru(II)(terpy)(2) (1, terpy = 2,2':6',2''-terpyridine) as a catalyst in the Belousov-Zhabotinsky (BZ) oscillating chemical reaction. We also examine several additional Ru(II) complexes, Ru(II)(bipy)(2)(L')(2) (2, L' = 4-pyridinecarboxylic acid; bipy = 2,2'-bipyridine) and Ru(II)(bipy)(2)(L'') (3, L'' = 4,4'-dicarboxy-2,2'-bipy; 4, L'' = N-allyl-4'-methyl-[2,2'-bipy]-4-carboxamide; 5, L'' = bipy), for catalyzing the BZ reaction. While 2 is unable to trigger BZ oscillations, probably because of the rapid loss of L' in a BZ solution, the other bipyridine-based Ru(II)-complexes can catalyze the BZ reaction, although their catalytic activity is adversely affected by slow ligand substitution in a BZ solution. Nevertheless, the successfully tested Ru(II)(terpy)(2) and Ru(II)(bipy)(2)(L'') catalysts may provide useful building blocks for complex functional macromolecules.