A Pyrene-Based N-Heterocyclic Carbene: Study of Its Coordination Chemistry and Stereoelectronic Properties
摘要:
A new pyrene-N-heterocyclic carbene ligand has been obtained and coordinated to rhodium and iridium, affording the corresponding [MCl(NHC)(COD)] and [MCl(NHC)(CO)(2)] complexes (M = Ir, Rh). The presence of the pyrene backbone allows the introduction of a eta(6)-bonded [RuCp](+) fragment and facilitates the formation of the corresponding heterometallic complexes of Rh/Ru and Ir/Ru. The stereoelectronic properties of the new ligand have been studied by means of IR spectroscopy and cyclic voltammetry and demonstrate that the introduction of the [RuCp](+) fragment results in the reduction of the electron-donating power of the ligand.
Polyannulated Bis(N-heterocyclic carbene)palladium Pincer Complexes for Electrocatalytic CO<sub>2</sub> Reduction
作者:Jeffrey A. Therrien、Michael O. Wolf、Brian O. Patrick
DOI:10.1021/acs.inorgchem.5b01698
日期:2015.12.21
Phenanthro- and pyreno-annulated N-heterocyclic carbenes (NHCs) have been incorporated into lutidine-linked bisNHC Pd pincer complexes to investigate the effect of these polyannulated NHCs on the ability of the complexes to electro-chemically reduce CO2 to CO in the presence of 2,2,2-trifluoroacetic acid and 2,2,2-trifluoroethanol as proton sources. These complexes are screened for their ability to reduce CO, and modeled using density functional theory calculations, where the annulated phenanthrene and pyrene moieties are shown to be additional sites for redox activity in the pincer ligand, enabling increased electron donation. Electrochemical and computational studies are used to gain an understanding of the chemical significance of redox events for complexes of this type, highlighting the importance of anion binding and dissociation.