Structural and electrochemical investigations of new mononuclear nickel(II) dithiolate complexes bearing a pendant amine

Abstract

To further develop the biomimetic chemistry of [FeFe]- and [NiFe]-hydrogenases for the catalytic reduction of protons to hydrogen (H2), two new mononuclear Ni(II) ethanedithiolate complexes [{(Ph2PCH2)2NR}Ni(SCH2CH2S)] (R = tert-butyl (Bu t ), 1 and n-butyl (Bu n ), 2) with pendant amine-containing diphosphines were synthesized in moderate yields from the treatments of mononickel dichlorides [{(Ph2PCH2)2NR}NiCl2] with ethanedithiol (HSCH2CH2SH) with triethylamine (Et3N) as an acid-binding agent at room temperature. The as-prepared complexes 1 and 2 have been fully characterized by means of elemental analysis, nuclear magnetic resonance (NMR) spectrum, and X-ray crystallography. Further, the electrochemical properties of 1 and 2 are investigated in the absence or presence of acetic acid (HOAc) by using cyclic voltammetry (CV), suggesting that they can be considered as the active electrocatalysts for proton reduction to H2.