Hard vs soft Ni–Fe catalysts for making hydrogen

A matrix of S-bridged Ni–Fe nitrosyl complexes shows how NO ‘softness’ trades catalytic potential against acid strength and TOF in HER.

Keep what you just learned

Save these 11 cards to your NoteFren library. Your first review starts right away, and each card links back to the study it came from.

What core structure do all these HER catalysts share?

A butterfly-like [M(μ-SR)2Fe] dithiolate core.

How do NO ligands change catalytic performance?

They confer electron uptake at milder potentials but require stronger acid and give lower TOF.

What faradaic efficiencies were measured for the nitrosylated pair?

68 ± 2% and 58 ± 1% for H2.

What FE did [Ni–Fe′]+ give?

About 96%.

What CV TOF is reported for [Ni–Fe]+?

39.7 s−1 versus 26.7 s−1 for the comparison complex.

How was H2 confirmed after electrolysis?

Constant potential at −1.12 V for 60 min and GC of the headspace.

What acid-equivalence onset is noted for the first cathodic response?

It saturates with ~20 equivalents of acid.

What H2-release mechanisms do computations assign?

Heterolytic H−/H+ coupling for a–c and reductive elimination for soft–soft d.

Why is the NO ligand called non-innocent here?

It confers electron uptake at milder potentials on both donor and acceptor units.

Are these highly efficient HER catalysts?

Only moderately efficient, but well-behaved and reproducible.

What HSAB-style language do the authors use?

Soft vs hard donor/receiver units indexed by the number of NO ligands (0 to 3).