Redox reactions of [FeFe]-hydrogenase models containing an internal amine and a pendant phosphine

• A diiron dithiolate complex with a pendant phosphine coordinated to one of the iron centers, [(μ-SCH2)2N(CH2C 6H4-o-PPh2){Fe2(CO)5}] (1), was prepared and structurally characterized. The pendant phosphine is dissociated together with a CO ligand in the presence of excess PMe3, to afford [(μ-SCH2)2N(CH2C 6H4-o-PPh2){Fe(CO)2(PMe 3)}2] (2). Redox reactions of 2 and related complexes were studied in detail by in situ IR spectroscopy. A series of new Fe IIFeI ([3]+ and [6]+), Fe IIFeII ([4]2+), and FeIFe I (5) complexes relevant to Hox, Hox CO, and Hred states of the [FeFe]-hydrogenase active site were detected. Among these complexes, the molecular structures of the diferrous complex [4]2+ with the internal amine and the pendant phosphine co-coordinated to the same iron center and the triphosphine diiron complex 5 were determined by X-ray crystallography. To make a comparison, the redox reactions of an analogous complex, [(μ-SCH2)2N(CH 2C6H5){Fe(CO)2(PMe 3)}2] (7), were also investigated by in situ IR spectroscopy in the absence or presence of extrinsic PPh3, which has no influence on the oxidation reaction of 7. The pendant phosphine in the second coordination sphere makes the redox reaction of 2 different from that of its analogue 7.

Ämnesord

NATURVETENSKAP  -- Kemi -- Oorganisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)

Nyckelord

Fe-Only Hydrogenase

H-Ox State

Density-Functional Theory

Diiron Dithiolate Model

X-Ray Structures

Active-Site

Mixed-Valent

Clostridium-Pasteurianum

Iron Hydrogenase

Complexes

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