Intramolecular stabilization of a catalytic [FeFe]-hydrogenase mimic investigated by experiment and theory

• Published in: Dalton transactions : an international journal of inorganic chemistry 2018-04, Vol.47 (14), p.4941-4949
• Main Authors: Pandey, Indresh Kumar, Natarajan, Mookan, Faujdar, Hemlata, Hussain, Firasat, Stein, Matthias, Kaur-Ghumaan, Sandeep
• Format: Article
• Language: English
• Subjects: Acetic acid; Amino acids; Carbonyls; Catalysis; Crystal structure; Electrochemistry; Hydrogen evolution reactions; Hydrogenase; Intermetallic compounds; Iron compounds; Ligands; Naphthalene; Nickel compounds; Stabilization
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c7dt04837h

The mono-substituted complex [Fe 2 (CO) 5 (μ-naphthalene-2-thiolate) 2 (P(PhOMe- p ) 3 )] was prepared taking after the structural principles from both [NiFe] and [FeFe]-hydrogenase enzymes. Crystal structures are reported for this complex and the all carbonyl analogue. The bridging naphthalene thiolates resemble μ-bridging cysteine amino acids. One of the naphthyl moieties forms π-π stacking interactions with the terminal bulky phosphine ligand in the crystal structure and in calculations. This interaction stabilizes the reduced and protonated forms during electrocatalytic proton reduction in the presence of acetic acid and hinders the rotation of the phosphine ligand. The intramolecular π-π stabilization, the electrochemistry and the mechanism of the hydrogen evolution reaction were investigated using computational approaches. A dinuclear [FeFe] complex was prepared based on the design principles from the two families of hydrogenase enzymes and is internally stabilized by weak interactions to enhance hydrogen production.