Electronic Communication in Di- and Tri- Nuclear Ruthenium Acetylide Complexes

The electronic properties of a suite of di- and tri-nuclear ruthenium bis(acetylide)-based complexes incorporating phenylene and naphthylene bridges have been explored experimentally and computationally. The complexes, [{trans-Ru(dmpe) 2 (C≡C t Bu)} 2 (μ-C≡C(2,6-C 10 H 6 )C≡C)], [{trans-Ru(dmpe) 2 (C≡C t Bu)} 2 (μ-C≡C(2,7-C 10 H 6 )C≡C)], and [{trans-Ru(dmpe) 2 (C≡C t Bu)} 3 (μ-(C≡C) 3 (1,3,5-C 6 H 3 )] were formed via the metathesis of terminal organic bisacetylenes with the methylruthenium complex, [trans-Ru(dmpe) 2 (CH 3 )(C≡C t Bu)], in the presence of methanol and under mild conditions. Spectroelectrochemical analyses of these species showed that the linearly π-conjugated 2,6-naphthylene bridge enabled better electronic communication between redox-active ruthenium-acetylide sites than the cross-conjugated 2,7-naphthylene bridge.