Synthesis of [Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](CN)<sub>2</sub>(CO)<sub>4</sub>]<sup>2–</sup> and Related Iron Selenoates

The dianion [Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](CN)<sub>2</sub>(CO)<sub>4</sub>]<sup>2-</sup> ([<b>2</b>]<sup>2-</sup>) is of interest for the preparation of the selenide analog of the active site of the [FeFe]-hydrogenases. The obvious route for its synthesis by cyanation of Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](CO)<sub>6</sub> (<b>3</b>) fails for reasons that this paper explains and resolves. We show that CN<sup>-</sup> cleaves Se-C bonds in <b>3</b>. For example, treatment of Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](CO)<sub>6</sub> with NEt<sub>4</sub>CN followed by CH<sub>3</sub>I gives substantial amounts of Fe<sub>2</sub>(μ-SeCH<sub>3</sub>)<sub>2</sub>(CO)<sub>6</sub>. Authentic [<b>2</b>]<sup>2-</sup> can be obtained by cyanation of Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](CO)<sub>5</sub>(pyridine). The <sup>77</sup>Se NMR data for [<b>2</b>]<sup>2-</sup> and <b>3</b> are reevaluated and explained. Attempts to prepare Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](PPh<sub>3</sub>)<sub>2</sub>(CO)<sub>4</sub> (<b>9</b>) by Me<sub>3</sub>NO-induced decarbonylation of <b>3</b> also suffers from degradation of the organoselenium ligand. Complex <b>9</b> was prepared instead by photosubstitution. The protonation of [<b>2</b>]<sup>2-</sup> and [Fe<sub>2</sub>[(μ-SCH<sub>2</sub>)<sub>2</sub>NH](CN)<sub>2</sub>(CO)<sub>4</sub>]<sup>2-</sup> are compared: the selenium compounds are more basic. The structure of [HFe<sub>2</sub>[(μ-SCH<sub>2</sub>)<sub>2</sub>NH](CN)<sub>2</sub>(CO)<sub>4</sub>]<sup>-</sup> was determined crystallographically.

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Publication Details

Journal
Organometallics
Published
2024-12-23
DOI
https://doi.org/10.1021/acs.organomet.4c00457
Citations
2
Primary Topic
Metalloenzymes and iron-sulfur proteins
Type
article
Field-Weighted Citation Impact
0.20

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article

Synthesis of [Fe2[(μ-SeCH2)2NH](CN)2(CO)4]2– and Related Iron Selenoates

Thomas B. Rauchfuss, Xin Yu, Toby J. Woods
2 citations
Organometallics
Metalloenzymes and iron-sulfur proteins
0.20
article

Synthesis of [Fe2[(μ-SeCH2)2NH](CN)2(CO)4]2– and Related Iron Selenoates

Thomas B. Rauchfuss, Xin Yu, Toby J. Woods
article en
2 citations

Abstract

The dianion [Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](CN)<sub>2</sub>(CO)<sub>4</sub>]<sup>2-</sup> ([<b>2</b>]<sup>2-</sup>) is of interest for the preparation of the selenide analog of the active site of the [FeFe]-hydrogenases. The obvious route for its synthesis by cyanation of Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](CO)<sub>6</sub> (<b>3</b>) fails for reasons that this paper explains and resolves. We show that CN<sup>-</sup> cleaves Se-C bonds in <b>3</b>. For example, treatment of Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](CO)<sub>6</sub> with NEt<sub>4</sub>CN followed by CH<sub>3</sub>I gives substantial amounts of Fe<sub>2</sub>(μ-SeCH<sub>3</sub>)<sub>2</sub>(CO)<sub>6</sub>. Authentic [<b>2</b>]<sup>2-</sup> can be obtained by cyanation of Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](CO)<sub>5</sub>(pyridine). The <sup>77</sup>Se NMR data for [<b>2</b>]<sup>2-</sup> and <b>3</b> are reevaluated and explained. Attempts to prepare Fe<sub>2</sub>[(μ-SeCH<sub>2</sub>)<sub>2</sub>NH](PPh<sub>3</sub>)<sub>2</sub>(CO)<sub>4</sub> (<b>9</b>) by Me<sub>3</sub>NO-induced decarbonylation of <b>3</b> also suffers from degradation of the organoselenium ligand. Complex <b>9</b> was prepared instead by photosubstitution. The protonation of [<b>2</b>]<sup>2-</sup> and [Fe<sub>2</sub>[(μ-SCH<sub>2</sub>)<sub>2</sub>NH](CN)<sub>2</sub>(CO)<sub>4</sub>]<sup>2-</sup> are compared: the selenium compounds are more basic. The structure of [HFe<sub>2</sub>[(μ-SCH<sub>2</sub>)<sub>2</sub>NH](CN)<sub>2</sub>(CO)<sub>4</sub>]<sup>-</sup> was determined crystallographically.

OrganometallicsVol. 44(1)
University of Illinois Urbana-Champaign (US)
National Institutes of Health, National Institute of General Medical Sciences
Openalex Percentile: Top 56%
Metalloenzymes and iron-sulfur proteins
0.20
DOIOpen Access PDFOpenAlex
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