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Conformational Effects of [Ni 2 (μ‐ArS) 2 ] Cores on Their Electrocatalytic Activity
Author(s) -
MondragónDíaz Alexander,
RoblesMarín Elvis,
MuruetaCruz Brenda A.,
Aquite Juan C.,
MartínezAlanis Paulina R.,
FloresAlamo Marcos,
Aullón Gabriel,
Benítez Luis Norberto,
Castillo Ivan
Publication year - 2019
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201901037
Subject(s) - overpotential , nickel , crystallography , chemistry , electrochemistry , bent molecular geometry , redox , ferrocene , ion , stereochemistry , inorganic chemistry , electrode , organic chemistry
Two nickel complexes supported by tridentate NS 2 ligands, [Ni 2 ( κ ‐ N , S , S , S′ ‐N Ph {CH 2 (MeC 6 H 2 R′)S} 2 ) 2 ] ( 1 ; R′=3,5‐(CF 3 ) 2 C 6 H 3 ) and [Ni 2 ( κ ‐ N , S , S , S′ ‐N iBu {CH 2 C 6 H 4 S} 2 ) 2 ] ( 2 ), were prepared as bioinspired models of the active site of [NiFe] hydrogenases. The solid‐state structure of 1 reveals that the [Ni 2 (μ‐ArS) 2 ] core is bent, with the planes of the nickel centers at a hinge angle of 81.3(5)°, whereas 2 shows a coplanar arrangement between both nickel(II) ions in the dimeric structure. Complex 1 electrocatalyzes proton reduction from CF 3 COOH at −1.93 (overpotential of 1.04 V, with i cat / i p ≈21.8) and −1.47 V (overpotential of 580 mV, with i cat / i p ≈5.9) versus the ferrocene/ferrocenium redox couple. The electrochemical behavior of 1 relative to that of 2 may be related to the bent [Ni 2 (μ‐ArS) 2 ] core, which allows proximity of the two Ni⋅⋅⋅Ni centers at 2.730(8) Å; thus possibly favoring H + reduction. In contrast, the planar [Ni 2 (μ‐ArS) 2 ] core of 2 results in a Ni⋅⋅⋅Ni distance of 3.364(4) Å and is unstable in the presence of acid.