Hybrids of [FeFe]- and [NiFe]-H 2 ase Active Site Models

• Published in: Organometallics Vol. 42; no. 13; pp. 1607 - 1614
• Main Authors: Zhang, Fanjun, Woods, Toby J, Rauchfuss, Thomas B
• Format: Journal Article
• Language: English
• Published: United States 10-07-2023
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/acs.organomet.3c00173

Complexes of the type (diphosphine)Ni(
-SR)
Fe(CO)
are investigated with azadithiolate (adt, HN(CH
S
)
) as the dithiolate. The resulting complexes are hybrid models for the active sites of the [NiFe]- and [FeFe]-hydrogenases. The key complex (dppv)Ni(
-adt)Fe(CO)
was prepared from the complex Ni[(SCH
)
NCbz](dppv), which contains a Cbz-protected adt ligand (Cbz = C(
)OCH
Ph, dppv =
-1,2-(Ph
P)
C
H
). This complex combines with Fe
(CO)
to give (dppv)Ni[(
-SCH
)
NCbz]Fe(CO)
, which is readily deprotected to give
. Complex
undergoes protonation at both Fe and N to give successively [(dppv)Ni(
-adt)FeH(CO)
]
([H
]
) and [(dppv)Ni(
-adtH)FeH(CO)
]
([H3H]
). The redox properties and dynamics of these complexes resemble previously reported analogues with propanedithiolate. Solutions of [H
]
readily degrade to [(dppv)Ni[(
-SCH
)
NCH
]Fe(CO)
]
([
]
), which features a methylene group linking N and Fe. Complex [
]
can be made in high yield by reaction of [H
]
with CH
O, and this conversion was also demonstrated with
CH
O. Complex [
]
undergoes hydrogenolysis by photochemical reaction with H
to give [(dppv)Ni[(
-SCH
)
NMe]FeH(CO)
]
, the
-methylated analogue of [
]
. Upon treatment ith Me
O
, [
]
undergoes quaternization, giving [(dppv)Ni[(
-SCH
)
N(Me)CH
]Fe(CO)
]
. In contrast with the lability of [H
]
, the phosphine-substituted derivative [(dppv)Ni(
-adt)FeH(CO)
(PPh
)]
did not degrade. Most complexes were characterized by X-ray crystallography.