Synthesis, characterization, and H/D exchange of µ-hydride-containing [FeFe]-hydrogenase subsite models formed by protonation reactions of (µ-TDT)Fe2(CO)4(PMe3)2 (TDT = SCH2SCH2S) with protic acids.

ABSTRACT

As [FeFe]-hydrogenase models, the first thiodithiolate (TDT) ligand-containing µ-hydride complexes [(µ-TDT)Fe2(CO)4(PMe3)2(µ-H)](+)Y(-) (2-7, Y = Cl, ClO4, PF6, BF4, CF3CO2, CF3SO3) have been prepared by protonation reactions of (µ-TDT)Fe2(CO)4(PMe3)2 (1) with the corresponding HY acids. While the protonation reactions are monitored by in situ(1)H and (31)P{(1)H} NMR spectroscopy to show the isomer type and stability of 2-7, the structures of the isolated 2-7 are characterized by elemental analysis, spectroscopy and for some of them by X-ray crystallography. Although the H/D exchange of µ-hydride complex 7 (Y = CF3SO3) with D2 or D2O has been proved not to occur under the studied conditions, the H/D exchange of 7 with DCl gives the µ-deuterium complex [(µ-TDT)Fe2(CO)4(PMe3)2(µ-D)](+)[CF3SO3](-) (8) in a nearly quantitative yield. To our knowledge, 8 is the first crystallographically characterized µ-deuterium-containing butterfly [2Fe2S] complex produced by H/D exchange reaction.