Synthesis, structure and electrochemistry of mononuclear and dinuclear ruthenium–thiophenecarboxylate complexes

Abstract

Three 3-thiophenecarboxylate-containing and one 2,2′-bithiophene-5-carboxylate-containing diruthenium complexes, [Ru 2(μ-O 2CR) 4(MeOH) 2]PF 6 (R = –C 4H 3S 1, –CH 2C 4H 3S 2, –CH CHC 4H 3S 3 and –C 8H 5S 2 4), were prepared using a facile carboxylate exchange reaction and characterized using elemental analysis, IR and UV–Vis spectroscopy. “Disassembly” of complexes 1– 4 using 1,2-bis(diphenylphosphino)-ethane (dppe) yielded the mononuclear ruthenium(II) complexes, [Ru(η 2-O 2CR)(dppe) 2]PF 6 (R = –C 4H 3S 5, –CH 2C 4H 3S 6, –CH CHC 4H 3S 7 and –C 8H 5S 2 8), which were characterized as above as well as by 1H and 31P NMR and single crystal X-ray analysis. All of the complexes were studied using cyclic voltammetry to assess the ability of the thiophene moieties to undergo oxidative polymerization with complex 4 showing the greatest promise.