Mechanistic studies on proton transfer in a [FeFe] hydrogenase mimic complex

作者：Wang Ying; Ahlquist Marten S G^*

来源：Dalton Transactions, 2013, 42(21): 7816-7822.

DOI：10.1039/c3dt33087g

Four different pathways for deprotonation of [(mu-pdt){Fe(CO)(3)}{Fe(CO)(kappa(2)-Me2PCH2N(Me)CH2PMe2)}] (pdt = propane-1,3-dithiolate) [1H(mu)](1+) were examined, including (1) the %26quot;Direct%26quot; deprotonation; (2) the %26quot;Indirect%26quot; deprotonation via the pendant amine N; (3) the %26quot;Indirect%26quot; deprotonation via the distal metal Fe; and (4) the %26quot;Indirect%26quot; deprotonation via the dithiolate S. Only deprotonation of the %26quot;Indirect%26quot; pathway via the pendant amine N is feasible at room temperature. The most favorable migration destination for the bridging hydride in [1H(mu)](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 %26quot;Indirect%26quot; 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 [1H(Fe)](1+) implies the high activity for the interaction with aniline.

• 出版日期2013