1 research outputs found
Highly Activated Terminal Carbon Monoxide Ligand in an Iron–Sulfur Cluster Model of FeMco with Intermediate Local Spin State at Fe
Nitrogenases, the enzymes that convert N2 to
NH3, also catalyze the reductive coupling of CO to yield
hydrocarbons.
CO-coordinated species of nitrogenase clusters have been isolated
and used to infer mechanistic information. However, synthetic FeS
clusters displaying CO ligands remain rare, which limits benchmarking.
Starting from a synthetic cluster that models a cubane portion of
the FeMo cofactor (FeMoco), including a bridging carbyne ligand, we
report a heterometallic tungsten–iron–sulfur cluster
with a single terminal CO coordination in two oxidation states with
a high level of CO activation (νCO = 1851 and 1751
cm–1). The local Fe coordination environment (2S,
1C, 1CO) is identical to that in the protein making this system a
suitable benchmark. Computational studies find an unusual intermediate
spin electronic configuration at the Fe sites promoted by the presence
the carbyne ligand. This electronic feature is partly responsible
for the high degree of CO activation in the reduced cluster