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Surprising Condensation Reactions of the Azadithiolate Cofactor.

Authors :: Zhang F
Richers CP
Woods TJ
Rauchfuss TB
Source :: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2021 Sep 13; Vol. 60 (38), pp. 20744-20747. Date of Electronic Publication: 2021 Aug 18.
Publication Year :: 2021
Abstract: Azadithiolate, a cofactor found in all [FeFe]-hydrogenases, is shown to undergo acid-catalyzed rearrangement. Fe <subscript>2</subscript> [(SCH <subscript>2</subscript> ) <subscript>2</subscript> NH](CO) <subscript>6</subscript> self-condenses to give Fe <subscript>6</subscript> [(SCH <subscript>2</subscript> ) <subscript>3</subscript> N] <subscript>2</subscript> (CO) <subscript>17</subscript> . The reaction, which is driven by loss of NH <subscript>4</subscript> <superscript>+</superscript> , illustrates the exchange of the amine group. X-ray crystallography reveals that three Fe <subscript>2</subscript> (SR) <subscript>2</subscript> (CO) <subscript>x</subscript> butterfly subunits interconnected by the aminotrithiolate [N(CH <subscript>2</subscript> S) <subscript>3</subscript> ] <superscript>3-</superscript> . Mechanistic studies reveal that Fe <subscript>2</subscript> [(SCH <subscript>2</subscript> ) <subscript>2</subscript> NR](CO) <subscript>6</subscript> participate in a range of amine exchange reactions, enabling new methodologies for modifying the adt cofactor. Ru <subscript>2</subscript> [(SCH <subscript>2</subscript> ) <subscript>2</subscript> NH](CO) <subscript>6</subscript> also rearranges, but proceeds further to give derivatives with Ru-alkyl bonds Ru <subscript>6</subscript> [(SCH <subscript>2</subscript> ) <subscript>3</subscript> N][(SCH <subscript>2</subscript> ) <subscript>2</subscript> NCH <subscript>2</subscript> ]S(CO) <subscript>17</subscript> and [Ru <subscript>2</subscript> [(SCH <subscript>2</subscript> ) <subscript>2</subscript> NCH <subscript>2</subscript> ](CO) <subscript>5</subscript> ] <subscript>2</subscript> S.<br /> (© 2021 Wiley-VCH GmbH.)