Nickel(II)–Nickel(II) Azadithiolates: Synthesis, Structural Characterization, and Electrocatalytic H₂ Production

Abstract

Azadithiolato-bridged dinuclear Ni2 complexes with the general formula [(η5-C5H5)­Ni­{(μ-SCH2)2NC6H4R-4}­Ni­(diphos)]­BF4 (8–11, R = H, Cl, MeO; diphos = dppv, dppe) have been prepared by a well-designed synthetic method including the following three separate reaction steps. The first reaction step involves preparation of the bis­(thioester) precursors 4-RC6H4N­(CH2S­(O)­CMe)2 (1–3, R = H, Cl, MeO) by a cocondensation reaction of aniline or its substituted derivatives 4-RC6H4NH2 with 37% aqueous formaldehyde and thioacetic acid. The second step involves preparation of the mononuclear Ni precursors (diphos)­Ni­[(SCH2)2NC6H4R-4] (4–7, R = H, Cl, MeO; diphos = dppv, dppe) by a one-pot reaction of bis­(thioester) precursors 1–3 with t-BuONa followed by treatment of the resulting disodium intermediates 4-RC6H4N­(CH2SNa)2 with (dppv)­NiCl2 and (dppe)­NiCl2, respectively. The third step involves preparation of the targeted dinuclear Ni2 complexes 8–11 by coordination reactions of mononuclear Ni precursors 4–7 with [η5-C5H5Ni]+ generated in situ from dissociation of the triple-decker sandwich complex [(C5H5)3Ni2]­BF4. While all of the prepared compounds 1–11 have been characterized by elemental analysis and various spectroscopic techniques, the molecular structures of precursor complex 5 and targeted complexes 9 and 11 have been further confirmed by X-ray crystallography. In addition, the two representative targeted complexes 8 and 9 have been found to be catalysts for proton reduction to hydrogen using acetic acid as the proton source under electrochemical conditions.

PCP Pincer Carbene Nickel(II) Chloride, Hydride, and Thiolate Complexes: Hydrosilylation of Aldehyde, Ketone, and Nitroarene by the Thiolate Complex

“…Metal complexes containing the M–X bond (X = RO – , RS – , R 2 N – ) are highly useful as catalysts for making C-heteroatom bonds. , Of these a large number of metal thiolates have been used to understand the reactions of many metalloenzymes and catalytic hydrogen production. − In addition, several metal thiolates containing different ancillary ligands have been studied for their metal–ligand cooperation in catalytic reactions. − …”

Functionalized nickel(ii)–iron(ii) dithiolates as biomimetic models of [NiFe]-H2ases

“…Typically, such an observation demonstrates that [ 2 ]PF 6 has the electrocatalytic H 2 -producing ability from TFA at a potential nearby its original second reduction potential. 46,47…”

“…Typically, such an observation demonstrates that [2]PF 6 has the electrocatalytic H 2 -producing ability from TFA at a potential nearby its original second reduction potential. 46,47 Further evidence for the electrocatalytic H 2 production catalyzed by [2]PF 6 was obtained by bulk electrolysis (BE) of a MeCN solution of [2]PF 6 (1.0 mM) with excess TFA (50 mM) at a potential slightly beyond its original second reduction peak. During 2 h of the BE process, a total amount of 36 F mol −1 passed through the cell, which corresponds to a theoretical turnover number (TON) of 18.…”