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A model of the iron hydrogenase active site with the structure [(μ-ADT)Fe₂(CO)₆] (ADT = azadithiolate (S−CH₂−NR−CH₂−S), (2:  R = 4-bromophenyl, 3:  R = 4-iodophenyl)) has been assembled and covalently linked to a [Ru(terpy)₂]²⁺ photosensitizer. This trinuclear complex 1 represents one synthetic step toward the realization of our concept of light-driven proton reduction. A rigid phenylacetylene tether has been incorporated as the linking unit in 1 in order to prolong the lifetime of the otherwise short-lived [Ru(terpy)₂]²⁺ excited state. The success of this strategy is demonstrated by comparison of the photophysical properties of 1 and of two related ruthenium complexes bearing acetylenic terpyridine ligands, with those of [Ru(terpy)₂]²⁺. IR and electrochemical studies reveal that the nitrogen heteroatom of the ADT bridge has a marked influence on the electronic properties of the [Fe₂(CO)₆] core. Using the Rehm …