Studies of Ligand Exchange in N-Heterocyclic Carbene Silver(I) Complexes

Abstract

A series of N-heterocyclic carbene (NHC) Ag(I) complexes have been prepared and used to study the dynamics of NHC ligand exchange in these Ag(I) complexes. These studies used solution-state variable-temperature (VT) 13 C NMR spectroscopy and the temperature-dependent changes in 13 C− 107/109 Ag coupling to determine activation energies for the ligand exchange process. The effects of concentration, bridging anions, and additives on the exchange process have been studied. The experimental activation energies for the NHC ligand exchange processes of these silver complexes are also compared with DFT calculations. The results are consistent with an associative mechanism for the Ag(I)−NHC exchange process.

CO2 Hydrogenation to Formate with Immobilized Ru‐Catalysts Based on Hybrid Organo‐Silica Mesostructured Materials

“…In order to obtain molecular‐level characterization of the surface species, the corresponding 13 C‐labeled catalyst at the NHC carbenic carbon was prepared with 13 C‐labeled 1‐mesityl‐1H‐imidazole . The immobilized 13 C‐enriched imidazolium precursor – ca.…”

Carboxylate-Functionalized Mesoionic Carbene Precursors: Decarboxylation, Ruthenium Bonding, and Catalytic Activity in Hydrogen Transfer Reactions

“…Moreover, the fluxionality of silver coordination and the equilibrium between neutral [AgX(carbene)] species and cationic complexes [Ag(L)(carbene)] + (L = pyridyl, triazolylidene) is expected to further complicate the product mixture. 57,58 The lability of the carboxylic moiety in 3 may open up new opportunities for the metalation of triazolium salts via decarboxylative methods. 46,47 However, all our attempts to Organometallics XXXX, XXX, XXX−XXX C use the carboxylate group as a carbene transfer agent to ruthenium(II) have been unsuccessful so far.…”

Synthesis, Characterization and Luminescence of Gold Complexes Bearing an NHC Ligand Based on the Imidazo[1,5‐a]quinolinol Scaffold

“…However, the 13 C NMR shifts of the carbene carbon atoms of the two forms are too similar to allow the isomers to be distinguished. [20] A thorough investigation of 4 was further hampered by the instability of the compound in solution: no 13 C NMR spectrum could be recorded because of decomposition during the measurement. Therefore we compared the molar conductivity of 4 with the molar conductivity of a previously reported ionic complex [(NHC) 2 1 H NMR spectra, the resonance of the imidazolium proton at δ = 10.83 ppm (in [D 6 ]dmso) vanishes upon complex formation.…”