Effects of different ligands on the binding of a palladium center in a pyridyl spaced dicarbene

Abstract

The reduction of carbon dioxide by two electrons to generate carbon monoxide is an energetically uphill transformation with implications for solar fuel production. Accordingly, we have developed a suite of compounds consisting of [PDCRPdL]X–, (R= methyl, ethyl, isopropyl, cyclohexyl, 2,6-diisopropylphenyl and mesityl, L= bromide, acetonitrile, pyridine, and t-butylisocyanide, X–= Br–, 2 PF6–), where PDCR is a pyridine bridged N-heterocyclic carbene pincer ligand. These compounds have been characterized by NMR and IR spectroscopies. Furthermore, X-ray crystallography has permitted the solid-state structures of these complexes to be determined. VT-NMR and IR experiments have allowed for the thermodynamics and kinetics of small molecule binding by this family of complexes to be probed. The subtle interplay between ligand electronics and molecular cleft accessibility will be discussed in terms of catalyst design for CO2 conversion.