Electrocatalytic Hydrogen Evolution and Oxidation with Rhenium Tris(thiolate) Complexes: A Competition between Rhenium and Sulfur for Electrons and Protons
2020
Recent electrochemical experiments reveal that the rhenium-tris(thiolate) [ReL3] (L = DPPBT = diphenylphosphinoben-zenethiolate, a noninnocent ligand) complex catalytically reduces protons and oxidizes H2 (J. Am. Chem. Soc. 2015, 137, 9238). Direct calculations of redox potentials (E0), acidity constants (pKa), and free energies of activation (G‡) by density functional theory (DFT) with the help of high-level ab initio calculations predict that hydrogen oxidation reaction (HOR) thermodynamically and kinetically favors a Re-hydride/monothiol intermediate, while the hydrogen evolving reaction (HER) favors Re-dihydride intermediates, in contrast to the Re-dithiols as proposed previously. The catalytic pathway for HOR involves two oxidation steps from [ReL3] to [ReL3]2+, followed by H2 addition to form the Re-hydride/thiol, [(ReH)(S1H)L2]2+. Under basic conditions, deprotonation of this complex produces [Re(S1H)L2]+ with the thiol as S1, rather than the proposed S3. Further deprotonation of [Re(S1H)L2]+ clos...
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
154
References
11
Citations
NaN
KQI