A Heterobimetallic W–Ni Complex Containing a Redox-Active W[SNS]₂ Metalloligand

Abstract

The tungsten complex W[SNS]2 ([SNS]H3 = bis(2-mercapto-4-methylphenyl)amine) was bound to a Ni(dppe) [dppe = 1,2-bis(diphenylphosphino)ethane] fragment to form the new heterobimetallic complex W[SNS]2Ni(dppe). Characterization of the complex by single-crystal X-ray diffraction revealed the presence of a short W-Ni bond, which renders the complex diamagnetic despite formal tungsten(V) and nickel(I) oxidation states. The W[SNS]2 unit acts as a redox-active metalloligand in the bimetallic complex, which displays four one-electron redox processes by cyclic voltammetry. In the presence of the organic acid 4-cyanoanilinium tetrafluoroborate, W[SNS]2Ni(dppe) catalyzes the electrochemical reduction of protons to hydrogen coincident with the first reduction of the complex.

Heterobimetallic and Heterotrimetallic Clusters Containing a Redox‐Active Metalloligand

“…In the solid state, single‐crystal X‐ray diffraction experiments showed 2 to be a heterobimetallic complex with a bond between the molybdenum and nickel centers, isostructural with the W–Ni derivative . Complex 2 crystallized in the primitive space group P 2 1 / c .…”

Heterodinuclear Ni/M (M = Mo, W) Complexes Relevant to the Active Site of [NiFe]-Hydrogenases: Synthesis, Characterization, and Electrocatalytic H2 Evolution

“…However, in contrast to the internuclear separation between Ni II and Mo II in 2a , b being much longer than the sum of the covalent radii (Ni, 1.24 Å; Mo, 1.54 Å), the Ni II /W II internuclear separation in 4a (2.6201 Å) and 4b (2.5904 Å) is much less than the sum of the covalent radii (Ni, 1.24 Å; W, 1.62 Å), which implies that there exists a Ni/W metal–metal bond in each of complexes 4a , b . It should be noted that the Ni/W metal–metal bonds in 4a , b are slightly longer than that (2.5358 Å) of the previously reported for Ni I /W V complex …”

“…Although the electrochemical properties of some dinuclear Ni II /M 0 (M = Mo, W), ,, Ni I /Mo V or Ni 0 /Mo VI , and Ni I /W V complexes were previously studied by means of CV techniques, the electrochemical and electrocatalytic properties of dinuclear Ni II /M II (M = Mo, W)-based [NiFe]-H 2 ase models have not been systematically investigated, so far. To know the electrochemical properties of our Ni II /M II complexes, we chose 2a , b and 4b , c as representatives (note that 2a , b and 4b , c are suitable representatives of 2a – c and 4a – c since they contain all the different metals Mo/W and different substituents R 1 /R 2 included in 2a – c and 4a – c ) to determine their cyclic voltammograms by using n -Bu 4 NPF 6 as the supporting electrolyte in MeCN at a scan rate of 100 mV s –1 .…”

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

“…Inspired by the well-elucidated structure shown in Figure a, synthetic chemists have prepared a large number of the hetero- and homodinuclear Ni–M (M = Fe, Ru, Mn, Mo, W, Co, Ni, etc. )-based biomimetic mimics for [NiFe]-H 2 ases, but none of them contain the azadithiolato type of ligand. − Recently, considering that the bridging azadithiolato ligand in the active site of [FeFe]-H 2 ases can play a key role in the catalytic redox reaction between H 2 and protons − and in order to further develop the biomimetic chemistry of [NiFe]-H 2 ases, we decided to prepare the first azadithiolato ligand containing dinuclear Ni 2 complexes in which each of the azadithiolato 4-RC 6 H 4 N­(CH 2 S) 2 ligands is bridged between the two Ni atoms in CpNi and (diphosphine)­Ni moieties (Figure b). Fortunately, we have successfully synthesized and structurally characterized such a type of dinuclear Ni 2 complex and in particular some of them have been found to be catalysts for proton reduction to H 2 under CV conditions.…”