Abstract
The [Ni(PR2NR′2)2]2+ family of complexes are exceptionally active catalysts for proton reduction to H2. In this manuscript, we explore the first protonation step of the proposed catalytic cycle by using a catalytically inactive NiI complex possessing a sterically demanding variation of the ligand. Due to the paramagnetic nature of the NiI oxidation state, the protonated NiI intermediate has been characterized through a combination of cyclic voltammetry, electron nuclear double resonance (ENDOR) spectroscopy, and hyperfine sublevel correlation (HYSCORE) spectroscopy. Both the electrochemical and spectroscopic studies indicate that the NiI complex is protonated at a pendant amine that is endo to Ni, which suggests the presence of an intramolecular NiI⋯HN bonding interaction. Using density functional theory, the hydrogen bond was found to involve three doubly-occupied, localized molecular orbitals: the 3dxz, 3d z 2, and 3dyz orbitals of nickel. These studies provide the first direct experimental evidence for this critical catalytic intermediate, and implications for catalytic H2 production are discussed.
| Original language | English |
|---|---|
| Pages (from-to) | 10338-10347 |
| Number of pages | 10 |
| Journal | Chemistry - A European Journal |
| Volume | 21 |
| Issue number | 29 |
| DOIs | |
| Publication status | Published - Jul 1 2015 |
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Keywords
- electrochemistry
- hydrogen
- HYSCORE
- nickel
- protonation
ASJC Scopus subject areas
- Chemistry(all)
Cite this
Combined Spectroscopic and Electrochemical Detection of a NiI⋯H-N Bonding Interaction with Relevance to Electrocatalytic H2 Production. / Kochem, Amélie; O'Hagan, Molly; Wiedner, Eric; Van Gastel, Maurice.
In: Chemistry - A European Journal, Vol. 21, No. 29, 01.07.2015, p. 10338-10347.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Combined Spectroscopic and Electrochemical Detection of a NiI⋯H-N Bonding Interaction with Relevance to Electrocatalytic H2 Production
AU - Kochem, Amélie
AU - O'Hagan, Molly
AU - Wiedner, Eric
AU - Van Gastel, Maurice
PY - 2015/7/1
Y1 - 2015/7/1
N2 - The [Ni(PR2NR′2)2]2+ family of complexes are exceptionally active catalysts for proton reduction to H2. In this manuscript, we explore the first protonation step of the proposed catalytic cycle by using a catalytically inactive NiI complex possessing a sterically demanding variation of the ligand. Due to the paramagnetic nature of the NiI oxidation state, the protonated NiI intermediate has been characterized through a combination of cyclic voltammetry, electron nuclear double resonance (ENDOR) spectroscopy, and hyperfine sublevel correlation (HYSCORE) spectroscopy. Both the electrochemical and spectroscopic studies indicate that the NiI complex is protonated at a pendant amine that is endo to Ni, which suggests the presence of an intramolecular NiI⋯HN bonding interaction. Using density functional theory, the hydrogen bond was found to involve three doubly-occupied, localized molecular orbitals: the 3dxz, 3d z 2, and 3dyz orbitals of nickel. These studies provide the first direct experimental evidence for this critical catalytic intermediate, and implications for catalytic H2 production are discussed.
AB - The [Ni(PR2NR′2)2]2+ family of complexes are exceptionally active catalysts for proton reduction to H2. In this manuscript, we explore the first protonation step of the proposed catalytic cycle by using a catalytically inactive NiI complex possessing a sterically demanding variation of the ligand. Due to the paramagnetic nature of the NiI oxidation state, the protonated NiI intermediate has been characterized through a combination of cyclic voltammetry, electron nuclear double resonance (ENDOR) spectroscopy, and hyperfine sublevel correlation (HYSCORE) spectroscopy. Both the electrochemical and spectroscopic studies indicate that the NiI complex is protonated at a pendant amine that is endo to Ni, which suggests the presence of an intramolecular NiI⋯HN bonding interaction. Using density functional theory, the hydrogen bond was found to involve three doubly-occupied, localized molecular orbitals: the 3dxz, 3d z 2, and 3dyz orbitals of nickel. These studies provide the first direct experimental evidence for this critical catalytic intermediate, and implications for catalytic H2 production are discussed.
KW - electrochemistry
KW - hydrogen
KW - HYSCORE
KW - nickel
KW - protonation
UR - http://www.scopus.com/inward/record.url?scp=84934271073&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84934271073&partnerID=8YFLogxK
U2 - 10.1002/chem.201500954
DO - 10.1002/chem.201500954
M3 - Article
AN - SCOPUS:84934271073
VL - 21
SP - 10338
EP - 10347
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 29
ER -