RESUMO
Carbon-carbon bond-forming reductive elimination from elusive organocopper(III) complexes has been considered the key step in many copper-catalyzed and organocuprate reactions. However, organocopper(III) complexes with well-defined structures that can undergo reductive elimination are extremely rare, especially for the formation of Csp3-Csp3 bonds. We report herein a general method for the synthesis of a series of [alkyl-CuIII-(CF3)3]- complexes, the structures of which have been unequivocally characterized by NMR spectroscopy, mass spectrometry, and X-ray crystal diffraction. At elevated temperature, these complexes undergo reductive elimination following first-order kinetics, forming alkyl-CF3 products with good yields (up to 91%). Both kinetic studies and DFT calculations indicate that the reductive elimination to form Csp3-CF3 bonds proceeds through a concerted transition state, with a Δ H⧧ = 20 kcal/mol barrier.
RESUMO
Capped chelating organic molecules are presented as a design principle for tuning heterogeneous nanoparticles for electrochemical catalysis. Gold nanoparticles (AuNPs) functionalized with a chelating tetradentate porphyrin ligand show a 110-fold enhancement compared to the oleylamine-coated AuNP in current density for electrochemical reduction of CO2 to CO in water at an overpotential of 340â mV with Faradaic efficiencies (FEs) of 93 %. These catalysts also show excellent stability without deactivation (<5 % productivity loss) within 72 hours of electrolysis. DFT calculation results further confirm the chelation effect in stabilizing molecule/NP interface and tailoring catalytic activity. This general approach is thus anticipated to be complementary to current NP catalyst design approaches.