Probing the Electron Accepting Orbitals of Ni-Centered Hydrogen Evolution Catalysts with Noninnocent Ligands by Ni L-Edge and S K-Edge X-ray Absorption

Koroidov, Sergey (author): Stanford Univ, PULSE Inst, SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA;Stockholm Univ, Dept Phys, AlbaNova Univ Ctr, S-10691 Stockholm, Sweden

Hong, Kiryong (author): Stanford Univ, PULSE Inst, SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA;Korea Res Inst Stand & Sci, Ctr Gas Anal, Div Chem & Med Metrol, Daejeon 34113, South Korea

Kjaer, Kasper S. (author): Stanford Univ, PULSE Inst, SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA;Lund Univ, Dept Chem Phys, POB 124, S-22100 Lund, Sweden

Li, Lin (author): Stanford Univ, PULSE Inst, SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

Kunnus, Kristjan (author): Stanford Univ, PULSE Inst, SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

Reinhard, Marco (author): Stanford Univ, PULSE Inst, SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

Hartsock, Robert W. (author): Stanford Univ, PULSE Inst, SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

Amit, Das (author): Univ Rochester, Dept Chem, RC Box 270216, Rochester, NY 14627 USA;Univ Wisconsin, Dept Chem, 1101 Univ Ave, Madison, WI 53706 USA

Eisenberg, Richard (author): Univ Rochester, Dept Chem, RC Box 270216, Rochester, NY 14627 USA

Das Pemmaraju, C. (author): SLAC Natl Accelerator Lab, Theory Inst Mat & Energy Spectroscopies, Menlo Pk, CA 94025 USA

Gaffney, Kelly J. (author): Stanford Univ, PULSE Inst, SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

Cordones, Amy A. (author): Stanford Univ, PULSE Inst, SLAC Natl Accelerator Lab, Menlo Pk, CA 94025 USA

(creator_code:org_t)

2018-10-11
2018
English.
In: Inorganic Chemistry. - : AMER CHEMICAL SOC. - 0020-1669 .- 1520-510X. ; 57:21, s. 13167-13175

Related links:: https://www.osti.gov...; show more...; https://urn.kb.se/re...; https://doi.org/10.1...; show less...

Abstract Subject headings

The valence electronic structure of several square planar Ni-centered complexes, previously shown to catalyze the hydrogen evolution reaction, are characterized using S K-edge and Ni L-edge X-ray absorption spectroscopy and electronic structure calculations. Measurement of the atomic Ni 3d and S 3p contributions enables assessment of the metal-ligand covalency of the electron accepting valence orbitals and yields insight into the ligand-dependent reaction mechanisms proposed for the catalysts. The electron accepting orbital of the Ni(abt)(2) (abt = 2-aminobenzenethiolate) catalyst is found to have large ligand character (80%), with only 9% S 3p (per S) character, indicating delocalization over the entire abt ligand. Upon two proton-coupled reductions to form the Ni(abt-H)(2) intermediate, the catalyst stores 1.8 electrons on the abt ligand, and the ligand N atoms are protonated, thus supporting its role as an electron and proton reservoir. The electron accepting orbitals of the Ni(abt-H)(2) intermediate and Ni(mpo)(2) (mpo = 2-mercaptopyridyl-N-oxide) catalyst are found to have considerably larger Ni 3d (46-47%) and S 3p (17-18% per S) character, consistent with an orbital localized on the metal-ligand bonds. This finding supports the possibility of metal-based chemistry, resulting in Ni-H bond formation for the reduced Ni(abt-H)(2) intermediate and Ni(mpo)(2) catalyst, a critical reaction intermediate in H-2 generation.

By the author/editor: Koroidov, Sergey; Hong, Kiryong; Kjaer, Kasper S.; Li, Lin; Kunnus, Kristjan; Reinhard, Marco; show more...; Hartsock, Robert ...; Amit, Das; Eisenberg, Richa ...; Das Pemmaraju, C ...; Gaffney, Kelly J ...; Cordones, Amy A.; show less...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Chemical Science ...; and Inorganic Chemis ...

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