Ligand Substituents Govern the Efficiency and Mechanistic Path of Hydrogen Production with [Cp*Rh] Catalysts.

Autor: Henke WC; Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA., Lionetti D; Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA., Moore WNG; Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA., Hopkins JA; Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA., Day VW; Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA., Blakemore JD; Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS, 66045, USA.
Jazyk: angličtina
Zdroj: ChemSusChem [ChemSusChem] 2017 Nov 23; Vol. 10 (22), pp. 4589-4598. Date of Electronic Publication: 2017 Nov 02.
DOI: 10.1002/cssc.201701416
Abstrakt: We demonstrate that [Cp*Rh] complexes bearing substituted 2,2'-bipyridyl ligands are effective hydrogen evolution catalysts (Cp*=η 5 -pentamethylcyclopentadienyl). Disubstitution (at the 4 and 4' positions) of the bipyridyl ligand (namely -tBu, -H, and -CF 3 ) modulates the catalytic overpotential, in part due to involvement of the reduced ligand character in formally rhodium(I) intermediates. These reduced species are synthesized and isolated here; protonation results in formation of complexes bearing the unusual η 4 -pentamethylcyclopentadiene ligand, and the properties of these protonated intermediates further govern the catalytic performance. Electrochemical studies suggest that multiple mechanistic pathways are accessible, and that the operative pathway depends on the applied potential and solution conditions. Taken together, these results suggest synergy in metal-ligand cooperation that modulates the mechanisms of fuel-forming catalysis with organometallic compounds bearing multiple non-innocent ligands.
(© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
Databáze: MEDLINE
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