To date, a wide range of rhenium(I)-based CO2 reduction catalysts have been studied in the literature; however, very few feature phosphorus-donors, and none feature phosphazane ligands. Phosphazane ligands exhibit far greater tunability both in terms of electronic structure as well as steric demand, in comparison to other supporting ligands currently in use. Our work looks to expand the library of ligands currently used in CO2 reduction as well as other forms of small-molecule activation. A series of Re(I) chelating-phosphazane (PNP) complexes supported by polypyridyl and carbonyl ligands have been designed, synthesized, and in addition to routine characterization, their structural and electrochemical properties have been examined via single-crystal X-ray diffraction studies and cyclic voltammetry. Finding show that the monomeric Re(dppa)(bpy)(CO)2OTf (dppa = bis(diphenylphosphino)amine, bpy = 2,2'-bipyridine) complex reduces CO2 to CO and water in the presences of trifluoroethanol (TFE) with excellent catalyst longevity. Additionally, functionalized analogues of dppa have been synthesized and the ramifications of the electronic properties of the phosphazane ligands on electrocatalytic performance were assessed.

Novel rhenium(I) phosphazane complexes with applications towards electrocatalytic CO2 reduction

256th National Meeting (2018)

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