The Role of Solvent and the Outer Coordination Sphere on H2 Oxidation Using [Ni(PCy 2NPyz 2)2]2+

Arnab Dutta, Sheri Lense, John Roberts, Monte Helm, Wendy J. Shaw

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Hydrogenase enzymes are reversible catalysts for H2 production/oxidation, operating with fast rates and minimal overpotentials in water. Many synthetic catalyst mimics of hydrogenase operate in organic solvents. However, recent work has demonstrated the importance of water in the performance of some model complexes. In this work, the H2 oxidation activity of [Ni(PCy 2N(3-pyridazyl)methyl 2)2]2+ (CyPyz) was compared as a function of acetonitrile, methanol, and water. The reactivity was compared under neutral and acidic conditions in all three solvents and improvement in catalytic activity, from 2 to 40 s-1, was observed with increasing hydrogen bonding ability of the solvent. In addition, the overpotential for catalysis drops significantly in the presence of acid in all solvents, from as high as 600 mV to as low as 70 mV, primarily due to the shift in the equilibrium potential under these conditions. Finally, H2 production was also observed in the same solution, demonstrating bidirectional (irreversible) homogeneous H2 production/oxidation. A structurally and electronically similar complex with a benzyl instead of a pyridazyl group was not stable under these conditions, limiting the evaluation of the contributions of the outer coordination sphere. Collectively, we show that by tuning conditions we can promote fast, efficient H2 oxidation and bidirectional catalysis.

Original languageEnglish
Pages (from-to)5218-5225
Number of pages8
JournalEuropean Journal of Inorganic Chemistry
Volume2015
Issue number31
DOIs
Publication statusPublished - Nov 1 2015

Fingerprint

Hydrogenase
Oxidation
Catalysis
Water
Catalysts
Organic solvents
Methanol
Catalyst activity
Hydrogen bonds
Tuning
Acids
Enzymes
acetonitrile

Keywords

  • Bidirectional catalysis
  • Bioinspired catalyst design
  • Hydrogen oxidation
  • Solvent effects

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

The Role of Solvent and the Outer Coordination Sphere on H2 Oxidation Using [Ni(PCy 2NPyz 2)2]2+ . / Dutta, Arnab; Lense, Sheri; Roberts, John; Helm, Monte; Shaw, Wendy J.

In: European Journal of Inorganic Chemistry, Vol. 2015, No. 31, 01.11.2015, p. 5218-5225.

Research output: Contribution to journalArticle

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