A series of palladium SNS pincer complexes were synthesized featuring a pendant crown ether functionality. Characterization and electrochemical small molecule reactivity of the complexes containing group I and II metal cations are presented and compared to corresponding systems lacking cationic secondary sphere effects. It was found that incorporation of a group I or II metal shifts the onset of proton reduction up to 220 mV cathodic of complexes lacking crown ether functionality, even in the presence of excess group I/II metal salt in solution. This effect was observed utilizing proton sources of varying pKa in both acetonitrile and dimethylformamide solutions. We believe that the negative shift in the onset of proton reduction can be exploited to facilitate selective reduction of substrates requiring protons where hydrogen is an undesirable side-product. Progress towards utilization of electrostatic interactions to promote selective CO2 reduction to CO will be presented. Additionally, investigation into the origin of proton reduction inhibition in the presence of intramolecular cationic interactions will be discussed.

Turning off hydrogen evolution: Effects of secondary sphere electrostatic interactions on catalyst product selectivity

2019 Fall National Meeting

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