A great challenge in the [FeFe]-hydrogenase active site biomimetics is to obtain several features of the enzyme active site within one synthetic analogue. We have explored the effect of steric bulk at the nitrogen bridgehead of the S to S linker in (�-SCH2NRCH2S)[Fe(CO)3]2, where R = hydrogen, methyl, t-Butyl, in conjunction with CO-substituted with sterically bulky ligands, such as IMes (1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene). These two methods used to introduce steric bulk into the model complexes have previously been shown to aid in the synthesis of rotated structures, where the complexes contain a bridging carbonyl ligand. Both monosubstituted (�-SCH2NRCH2S)[Fe(CO)3]-[Fe(CO)2L], where L = PMe3, PPh3, and IMes (1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene), and disubstituted (�-SCH2NRCH2S)[Fe(CO)2L][Fe(CO)2L'], where L/L' = IMes/PMe3, IMes/PPh3, complexes have been prepared and analyzed by IR, X-ray diffraction, NMR, and cyclic voltametry.

Analysis of bridgehead effects on [FeFe]-hydrogenase active site models: Steric bulk at nitrogen vs. carbon

245th National Meeting (2013)

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