The ability to activate unfunctionalized C–H bonds provides a useful tool for converting simple chemical feedstocks into useful building blocks or inserting functional groups into complicated target molecules. The vast majority of successful molecular catalysts to date involve complexes of expensive second and third row transition metals. Nature, however, has developed highly efficient catalysts for C–H bond activation using iron. In cytochrome P450, for example, the use of redox non-innocent porphyrin and thiolate ligands on iron allows for multielectron processes to occur where the redox active ligand system provides the second electron equivalent. Taking inspiration from cytochrome P450, we are developing first-row metal complexes with redox non-innocent ligands that may lead to effective C–H bond activation catalysts. In addition, our systems incorporate functional groups to promote intramolecular non-covalent interactions within the secondary coordination sphere of the metal ion, which we argue will enhance reactivity by stabilizing key reactive intermediates. Towards this goal, we designed a tridentate sulfonamide ligand precursor, N,N′-(azanediylbis(2,1-phenylene))bis(2,4,6-triisopropylbenzenesulfonamide) (H3ibaps) and studied its coordination chemistry with first-row transition metals. Bipyridine and its derivatives were used to complete the coordination sphere to establish structure-function relationships within this family of complexes. Reactivities with substrates capable of secondary interactions with the [ipaps]3– ligand were also explored.

Redox non-innocent ligands on first row transition metals: Towards bio-inspired catalysts for C–H bond activation

251st National Meeting (2016)

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