title: Mechanistic studies on proton transfer in a [FeFe] hydrogenase mimic complex.
abstract: Four different pathways for deprotonation of [(μ-pdt){Fe(CO)3}{Fe(CO)(κ(2)-Me2PCH2N(Me)CH2PMe2)}] (pdt = propane-1,3-dithiolate) [1Hμ](1+) were examined, including (1) the "Direct" deprotonation; (2) the "Indirect" deprotonation via the pendant amine N; (3) the "Indirect" deprotonation via the distal metal Fe; and (4) the "Indirect" deprotonation via the dithiolate S. Only deprotonation of the "Indirect" pathway via the pendant amine N is feasible at room temperature. The most favorable migration destination for the bridging hydride in [1Hμ](1+) is the pendant amine N (activation energy barrier 16.1 kcal mol(-1)). Migrations to the other two possible sites including the distal metal Fe (34.6 kcal mol(-1)) and the S in the dithiolate group (41.5 kcal mol(-1)) were hindered by high proton shuttling barriers. Once the migration barriers of those three "Indirect" pathways are overcome, the following deprotonations from all three positions including the distal atom Fe, the dithiolate S and the pendant amine N, are all feasible. The results also demonstrate a large difference for deprotonation of the hydride from the terminal and bridging sites. The low energy of the virtual orbital associated with the antibonding M-H interaction of [1HFe](1+) implies the high activity for the interaction with aniline.
authors.affiliation: Division of Theoretical Chemistry & Biology, School of Biotechnology, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Mårten S G
authors.initials: MS
authors.lastname: Ahlquist
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D006864:Hydrogenase / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry*; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D008958:Models, Molecular; D011407:Propane / Q000031:analogs & derivatives* / Q000737:chemistry; D011522:Protons; D011789:Quantum Theory; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D058085:Iron Compounds; D007506:Iron-Sulfur Proteins; D011522:Protons; D013438:Sulfhydryl Compounds; C522648:propanedithiolate; C118830:iron hydrogenase; D006864:Hydrogenase; D011407:Propane