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The paper aims to elucidate the final stages in the biosynthesis of the [2Fe] H active site of the [FeFe]-hydrogenases. The recently hypothesized intermediate [Fe 2 (SCH 2 NH 2 ) 2 (CN) 2 (CO) 4 ] 2- ([1] 2- ) was prepared by a multistep route from [Fe 2 (S 2 )(CN)(CO) 5 ] - . The following synthetic intermediates were characterized in order: [Fe 2 (SCH 2 NHFmoc) 2 (CNBEt 3 )(CO) 5 ] - , [Fe 2 (SCH 2 NHFmoc) 2 (CN)-(CO) 5 ] - , and [Fe 2 (SCH 2 NHFmoc) 2 (CN) 2 (CO) 4 ] 2- , where Fmoc is fluorenylmethoxycarbonyl). Derivatives of these anions include [K(18-crown-6)] + , PPh 4 + and PPN + salts as well as the 13 CD 2 -isotopologues. These Fe 2 species exist as a mixture of two isomers attributed to diequatorial (ee) and axial-equatorial (ae) stereochemistry at sulfur. In vitro experiments demonstrate that [1] 2- maturates HydA1 in the presence of HydF and a cocktail of reagents. HydA1 can also be maturated using a highly simplified cocktail, omitting HydF and other proteins. This result is consistent with HydA1 participating in the maturation process and refines the roles of HydF., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Azadithiolate, a cofactor found in all [FeFe]-hydrogenases, is shown to undergo acid-catalyzed rearrangement. Fe 2 [(SCH 2 ) 2 NH](CO) 6 self-condenses to give Fe 6 [(SCH 2 ) 3 N] 2 (CO) 17 . The reaction, which is driven by loss of NH 4 + , illustrates the exchange of the amine group. X-ray crystallography reveals that three Fe 2 (SR) 2 (CO) x butterfly subunits interconnected by the aminotrithiolate [N(CH 2 S) 3 ] 3- . Mechanistic studies reveal that Fe 2 [(SCH 2 ) 2 NR](CO) 6 participate in a range of amine exchange reactions, enabling new methodologies for modifying the adt cofactor. Ru 2 [(SCH 2 ) 2 NH](CO) 6 also rearranges, but proceeds further to give derivatives with Ru-alkyl bonds Ru 6 [(SCH 2 ) 3 N][(SCH 2 ) 2 NCH 2 ]S(CO) 17 and [Ru 2 [(SCH 2 ) 2 NCH 2 ](CO) 5 ] 2 S., (© 2021 Wiley-VCH GmbH.)

The active site of the [FeFe]-hydrogenases features a binuclear [2Fe] H sub-cluster that contains a unique bridging amine moiety close to an exposed iron center. Heterolytic splitting of H 2 results in the formation of a transient terminal hydride at this iron site, which, however is difficult to stabilize. We show that the hydride intermediate forms immediately when [2Fe] H is replaced with [2Ru] H analogues through artificial maturation. Outside the protein, the [2Ru] H analogues form bridging hydrides, which rearrange to terminal hydrides after insertion into the apo-protein. H/D exchange of the hydride only occurs for [2Ru] H analogues containing the bridging amine moiety., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A victory in the pocket: An international team of chemists and biophysicists have resolved the long-standing question of the structure of the active site of the [FeFe] hydrogenases by assembling the active enzyme with a version of the active site synthesized in vitro (see scheme; HydF is a scaffold protein, HydA1 is a natural hydrogenase). The protein incorporating the diiron complex 2 showed similar activity to that of the natural enzyme., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nuclear inelastic scattering of (57)Fe labeled [NiFe] hydrogenase is shown to give information on different states of the enzyme. It was thus possible to detect and assign Fe-CO and Fe-CN bending and stretching vibrations of the active site outside the spectral range of the Fe-S cluster normal modes., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Not a poison! In contrast to the high reactivity of 1, the corresponding trihydride [ReH 3 (PMe 3 ) 4 ] is kinetically inert. Thus, the usual view that sulfur poisons catalysts is clearly inappropriate in this case. The catalytic properties of 1 result from its difunctional nature with both protic (SH) and hydridic (ReH) sites; these sites communicate by an intramolecular exchange process (see scheme; X=OMe, SH)., (© 2001 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.)

A volume of 132 Å 3 is enclosed by the title compound 1, which thus offers plenty of room for potential guest molecules. The synthesis from 2 [{Cp*RhCl 2 } 2 ] and 4 [CpCo(CN) 3 ] - begins with the construction of a "molecular square" whose corners are alternately occupied by Co and Rh centers. Two squares react with one another to give a "molecular box" without cleavage of any M-C bonds. Cp=C 5 H 5 , Cp*=C 5 Me 5 ., (© 1998 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.)