Abstract
A nickel complex has been synthesized using the P4N2 ligand, a tetradentate phosphine ligand with two pendant amines in the ligand backbone. The rigidly square pyramidal [Ni(P4N2)(CH3CN)]2+ complex is an electrocatalyst for the reduction of protons to hydrogen. Using N,N-dimethylformamidium ([DMF(H)+]) as the acid in an acetonitrile/water solution, [Ni(P4N2)(CH3CN)]2+ displays a turnover frequency of 1.6 × 106 s-1, which is among the fastest rates reported for any molecular electrocatalyst. This high catalytic rate comes at the cost of a 1200 mV overpotential at the catalytic half-wave potential. The Ni(II) state of the catalyst was found to be stable under strongly acidic conditions, with only trace decomposition observed over 2 weeks in the presence of 0.1 M trifluoromethanesulfonic acid (HOTf). The catalyst was less stable in the Ni(0) state due to the inability of the rigid P4N2 ligand to adopt a tetrahedral geometry. Using variable scan rate cyclic voltammetry, a first-order rate constant of ∼1 s-1 was measured for dissociation of a phosphine from Ni(0), which is proposed to be a key step for determining the lifetime of the catalyst during electrolysis.
| Original language | English |
|---|---|
| Journal | Organometallics |
| DOIs | |
| Publication status | Accepted/In press - Jan 1 2018 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry
Cite this
Electrocatalytic Hydrogen Production by a Nickel Complex Containing a Tetradentate Phosphine Ligand. / Klug, Christina M.; Dougherty, William G.; Kassel, W. Scott; Wiedner, Eric.
In: Organometallics, 01.01.2018.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Electrocatalytic Hydrogen Production by a Nickel Complex Containing a Tetradentate Phosphine Ligand
AU - Klug, Christina M.
AU - Dougherty, William G.
AU - Kassel, W. Scott
AU - Wiedner, Eric
PY - 2018/1/1
Y1 - 2018/1/1
N2 - A nickel complex has been synthesized using the P4N2 ligand, a tetradentate phosphine ligand with two pendant amines in the ligand backbone. The rigidly square pyramidal [Ni(P4N2)(CH3CN)]2+ complex is an electrocatalyst for the reduction of protons to hydrogen. Using N,N-dimethylformamidium ([DMF(H)+]) as the acid in an acetonitrile/water solution, [Ni(P4N2)(CH3CN)]2+ displays a turnover frequency of 1.6 × 106 s-1, which is among the fastest rates reported for any molecular electrocatalyst. This high catalytic rate comes at the cost of a 1200 mV overpotential at the catalytic half-wave potential. The Ni(II) state of the catalyst was found to be stable under strongly acidic conditions, with only trace decomposition observed over 2 weeks in the presence of 0.1 M trifluoromethanesulfonic acid (HOTf). The catalyst was less stable in the Ni(0) state due to the inability of the rigid P4N2 ligand to adopt a tetrahedral geometry. Using variable scan rate cyclic voltammetry, a first-order rate constant of ∼1 s-1 was measured for dissociation of a phosphine from Ni(0), which is proposed to be a key step for determining the lifetime of the catalyst during electrolysis.
AB - A nickel complex has been synthesized using the P4N2 ligand, a tetradentate phosphine ligand with two pendant amines in the ligand backbone. The rigidly square pyramidal [Ni(P4N2)(CH3CN)]2+ complex is an electrocatalyst for the reduction of protons to hydrogen. Using N,N-dimethylformamidium ([DMF(H)+]) as the acid in an acetonitrile/water solution, [Ni(P4N2)(CH3CN)]2+ displays a turnover frequency of 1.6 × 106 s-1, which is among the fastest rates reported for any molecular electrocatalyst. This high catalytic rate comes at the cost of a 1200 mV overpotential at the catalytic half-wave potential. The Ni(II) state of the catalyst was found to be stable under strongly acidic conditions, with only trace decomposition observed over 2 weeks in the presence of 0.1 M trifluoromethanesulfonic acid (HOTf). The catalyst was less stable in the Ni(0) state due to the inability of the rigid P4N2 ligand to adopt a tetrahedral geometry. Using variable scan rate cyclic voltammetry, a first-order rate constant of ∼1 s-1 was measured for dissociation of a phosphine from Ni(0), which is proposed to be a key step for determining the lifetime of the catalyst during electrolysis.
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U2 - 10.1021/acs.organomet.8b00548
DO - 10.1021/acs.organomet.8b00548
M3 - Article
JO - Organometallics
JF - Organometallics
SN - 0276-7333
ER -