Recently, our group has synthesized a multifunctional pyridyl-based pincer ligand containing two arms composed of a pyrazolyl and alkyl phosphine fragment. Deprotonation of the β-nitrogen of pyrazole ring on the 2-(5-(tert-butyl)-1H-pyraol-3-yl)-6-((di-tert-butylphosphanyl)methyl)pyridine (PNNH) ligand generates a donor site capable of coordinating an alkali or transition metal. Removal of a proton from the benzylic position forms a nucleophilic carbanion that can be delocalized into the pyridine ring. Through resonance, deprotonation of both acidic sites allows the ligand to stabilize metal centers in higher oxidation sites, a similar mechanism observed for redox active ligands (RALs). Carbonate is a sink for CO2 that has gained some attention by electrochemical reduction to organic compounds under aqueous conditions but conversion was slow. Reduction of carbonate coordinated to a metal complex bearing a proton responsive ligand might provide insight into mechanism. To that end, the synthesis of PNNHCo(CO3), characterization, and chemical reduction will be discussed.

Use of a multifunctional pincer in reductive conversions of carbonate

254th National Meeting (2017)

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