Diironcarbonyl-coumarin complex: preparation, intramolecular electron transfer, and electro-generation of hydrogen

Abstract

Electrochemical study was conducted using an Epsilon BAS potentiostat. Cyclic voltammograms were obtained using a three-electrode cell under nitrogen at room temperature. The electrodes used were a glassy carbon Keywords: Catalysis • Coumarin • Electron transfer • Hydrogenase model • OrganometallicA new organometallic complex coupling photoactive coumarin to a diironhexacarbonyl unit has been successfully prepared and its composition and electronic structure confirmed by elemental and spectroscopic analyses. Emission spectral analysis of the complex reveals photoinduced intramolecular electron transfer from coumarin to the iron-carbonyl moiety. The compound is electrochemically reduced at -1.24 V vs. Fc/Fc + . This reduction is irreversible, attesting to the instability of the complex. Electrochemical evolution of hydrogen in the presence of the complex has been studied and results are discussed.

Comparison of H2 photogeneration by [FeFe]-hydrogenase mimics with CdSe QDs and Ru(bpy)3Cl2 in aqueous solution

“…[23][24][25][26][27][28][29][30][31][32] Since the first attempt by Sun and Åkermark to construct an artificial photocatalytic system for H 2 evolution in 2003, 33 PS-Fe 2 S 2 molecular dyads connecting the PS and [Fe 2 S 2 ] catalytic center of [FeFe]-H 2 ase mimics have been reported. [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] However, these early dyads were unable to produce H 2 photochemically in homogeneous solution since the excited PS transferred energy rather than electrons to the [FeFe]-H 2 ase mimic catalyst. [33][34][35] Until 2008, several groups selected zinc(II) porphyrin or rhenium(I) polypyridyl complexes as the PS to construct PS-Fe 2 S 2 molecular dyads for photochemical H 2 evolution.…”

Synthesis, Characterization and Electrochemical Studies of bis(Monothiolato) {FeFe} Complexes [Fe2(μ‐SC6H4‐OMe‐m)2(CO)5L] (L = CO, PCy3, PPh3)

“…Only recently, the focus has shifted to monothiolate‐based {FeFe} systems. The limited examples reported include mostly hexacarbonyl and very few phosphine substituted mono‐ or diiron complexes [51–71] . Our group has also reported the redox and electrocatalytic properties of bis(monothiolato)‐based {FeFe} systems [72–77] wherein we have shown that the efficiency and stability of the catalysts vary with the type of monothiolate ligand used.…”

Insight on Mercapto-Coumarins: Synthesis and Reactivity

“…A diironhexacarbonyl cluster covalently linked to S-4-methyl coumarin ( 93 ) was synthesized ( Scheme 34 ) [ 90 ]. The complex, 93 , is electrochemically unstable and exhibited photoinduced intramolecular electron transfer from coumarin to the iron-carbonyl unit [ 90 ].…”