Terminal hydride in [FeFe]-hydrogenase model has lower potential for H2 production than the isomeric bridging hydride.
Protonation of the symmetrical tetraphosphine complexes Fe2(S2CnH2n)(CO)2(dppv)2 afforded the corresponding terminal hydrides, establishing that even symmetrical diiron(I) dithiolates undergo protonation at terminal sites. The terminal hydride [HFe2(S2C3H6)(CO)2(dppv)2](+) was found to catalyze proton reduction at potentials 200 mV milder than the isomeric bridging hydride, thereby establishing a thermodynamic advantage for catalysis operating via terminal hydride. The azadithiolate protonates to afford, [Fe2[(SCH2)2NH2](CO)2(dppv)2](+), [HFe2[(SCH2)2NH](CO)2(dppv)2](+), and [HFe2[(SCH2)2NH2](CO)2(dppv)2](2+), depending on conditions.
Barton
Bryan E
BE
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Rauchfuss
Thomas B
TB
D006859:Hydrogen / Q000737:chemistry* / Q000378:metabolism*; D006864:Hydrogenase / Q000737:chemistry* / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism*; D007536:Isomerism; D008954:Models, Biological; D008958:Models, Molecular
D007506:Iron-Sulfur Proteins; D006859:Hydrogen; C118830:iron hydrogenase; D006864:Hydrogenase