Abstract
Highly efficient electrocatalysts for both hydrogen evolution and hydrogen oxidation have been designed, synthesized, and characterized. The catalysts in their resting states are air-stable, mononuclear nickel(II) complexes containing cyclic diphosphine ligands with nitrogen bases incorporated into the ligand backbone. X-ray diffraction studies have established that the cation of [NI(PPh 2NPh2)2(CH 3CN)](BF4)2, 6a, (where PPh 2NPh 2 is 1,3,5,7-tetraphenyl-1,5-diaza-3,7- diphosphacyclooctane) is a trigonal bipyramid with bonds to four phosphorus atoms of the two bidentate diphosphine ligands and the nitrogen atom of an acetonitrile molecule. Two of the six-membered rings formed by the diphosphine ligands and Ni have boat conformations with an average Ni- - -N distance to the two pendant bases of 3.4 Å. The cation of [Ni(PCy 2NBz 2)2](BF4) 2, 6b, (where Cy = cyclohexyl and Bz = benzyl) is a distorted square planar complex. For 6b, all four six-membered rings formed upon coordination of the diphosphine ligands to the metal are in the boat form. In this case, the average Ni- - -N distance to the pendant base is 3.3 Å. Complex 6a is an electrocatalyst for hydrogen production in acidic acetonitrile solutions, and compound 6b is an electrocatalyst for hydrogen oxidation in basic acetonitrile solutions. It is demonstrated that the high catalytic rates observed with these complexes are a result of the positioning of the nitrogen base so that it plays an important role in the formation and cleavage of the H-H bond.
| Original language | English |
|---|---|
| Pages (from-to) | 358-366 |
| Number of pages | 9 |
| Journal | Journal of the American Chemical Society |
| Volume | 128 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 11 2006 |
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Hydrogen oxidation and production using nickel-based molecular catalysts with positioned proton relays. / Wilson, Aaron D.; Newell, Rachel H.; McNevin, Michael J.; Muckerman, James; DuBois, M. Rakowski; DuBois, Daniel L.
In: Journal of the American Chemical Society, Vol. 128, No. 1, 11.01.2006, p. 358-366.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Hydrogen oxidation and production using nickel-based molecular catalysts with positioned proton relays
AU - Wilson, Aaron D.
AU - Newell, Rachel H.
AU - McNevin, Michael J.
AU - Muckerman, James
AU - DuBois, M. Rakowski
AU - DuBois, Daniel L
PY - 2006/1/11
Y1 - 2006/1/11
N2 - Highly efficient electrocatalysts for both hydrogen evolution and hydrogen oxidation have been designed, synthesized, and characterized. The catalysts in their resting states are air-stable, mononuclear nickel(II) complexes containing cyclic diphosphine ligands with nitrogen bases incorporated into the ligand backbone. X-ray diffraction studies have established that the cation of [NI(PPh 2NPh2)2(CH 3CN)](BF4)2, 6a, (where PPh 2NPh 2 is 1,3,5,7-tetraphenyl-1,5-diaza-3,7- diphosphacyclooctane) is a trigonal bipyramid with bonds to four phosphorus atoms of the two bidentate diphosphine ligands and the nitrogen atom of an acetonitrile molecule. Two of the six-membered rings formed by the diphosphine ligands and Ni have boat conformations with an average Ni- - -N distance to the two pendant bases of 3.4 Å. The cation of [Ni(PCy 2NBz 2)2](BF4) 2, 6b, (where Cy = cyclohexyl and Bz = benzyl) is a distorted square planar complex. For 6b, all four six-membered rings formed upon coordination of the diphosphine ligands to the metal are in the boat form. In this case, the average Ni- - -N distance to the pendant base is 3.3 Å. Complex 6a is an electrocatalyst for hydrogen production in acidic acetonitrile solutions, and compound 6b is an electrocatalyst for hydrogen oxidation in basic acetonitrile solutions. It is demonstrated that the high catalytic rates observed with these complexes are a result of the positioning of the nitrogen base so that it plays an important role in the formation and cleavage of the H-H bond.
AB - Highly efficient electrocatalysts for both hydrogen evolution and hydrogen oxidation have been designed, synthesized, and characterized. The catalysts in their resting states are air-stable, mononuclear nickel(II) complexes containing cyclic diphosphine ligands with nitrogen bases incorporated into the ligand backbone. X-ray diffraction studies have established that the cation of [NI(PPh 2NPh2)2(CH 3CN)](BF4)2, 6a, (where PPh 2NPh 2 is 1,3,5,7-tetraphenyl-1,5-diaza-3,7- diphosphacyclooctane) is a trigonal bipyramid with bonds to four phosphorus atoms of the two bidentate diphosphine ligands and the nitrogen atom of an acetonitrile molecule. Two of the six-membered rings formed by the diphosphine ligands and Ni have boat conformations with an average Ni- - -N distance to the two pendant bases of 3.4 Å. The cation of [Ni(PCy 2NBz 2)2](BF4) 2, 6b, (where Cy = cyclohexyl and Bz = benzyl) is a distorted square planar complex. For 6b, all four six-membered rings formed upon coordination of the diphosphine ligands to the metal are in the boat form. In this case, the average Ni- - -N distance to the pendant base is 3.3 Å. Complex 6a is an electrocatalyst for hydrogen production in acidic acetonitrile solutions, and compound 6b is an electrocatalyst for hydrogen oxidation in basic acetonitrile solutions. It is demonstrated that the high catalytic rates observed with these complexes are a result of the positioning of the nitrogen base so that it plays an important role in the formation and cleavage of the H-H bond.
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U2 - 10.1021/ja056442y
DO - 10.1021/ja056442y
M3 - Article
VL - 128
SP - 358
EP - 366
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 1
ER -