Rhodium complexes functionalized by N-heterocyclic carbene ligands react with dioxygen to form adducts. Depending on the specifics of the ancillary ligands, oxygen binds to Rh either as a peroxide to form a fully oxidized Rh(III) complex, or as singlet dioxygen in a Rh(I) square planar complex. We have shown through analysis of a series of compounds, some previously published and some novel, that the presence of additional ligands that would support the formation of an octahedral geometry, as typically found with Rh(III) complexes, is critical for formation of the peroxide. In addition, we have demonstrated through DFT studies, that the potential energy surface with regard to the O-O bond length is relatively shallow, which provides a rationale for the distribution of bond lengths observed for apparently similar complexes analyzed by crystallography.
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http://dx.doi.org/10.1039/c3dt32264e | DOI Listing |
Dalton Trans
January 2025
Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC V8W 3 V6, Canada.
A charge-tagged N-heterocyclic carbene (NHC) has been synthesized and its utility in allowing the dynamic behaviour of metal complexes to be monitored in real time using electrospray ionization mass spectrometry demonstrated. This compound was used to prepare different metal-NHC complexes, and the kinetic behaviour of complex formation and ligand exchange was monitored in real time through the use of pressurized sample infusion electrospray mass spectrometry (PSI-ESI-MS).
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, Faculty of Science, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395, Japan.
The factors controlling the catalytic activity in photochemical hydrogen evolution reaction (HER) are studied in detail for two macrocyclic cobalt compounds bearing two N-heterocyclic carbenes and two pyridyl donors ( and , where has a methoxy substituent on each pyridyl ligand). The present study adopts an aqueous photosystem consisting of EDTA, [Ru(bpy)] (bpy = 2,2'-bipyridine), and MV (MV = methylviologen) at pH = 5. Both catalysts are shown to promote HER in a similar efficiency (TON = 12-13 in 6 h), revealing a minor contribution of the electron-donating methoxy substituents.
View Article and Find Full Text PDFOrg Lett
January 2025
Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials, College of Chemistry & Chemical Engineering, Anhui University, Hefei, Anhui 230601, China.
Boron compounds are widely employed in organic chemistry, pharmaceuticals, and materials science. Among them, borylated heterocycles serve as versatile synthons for the construction of new C-C or C-heteroatom bonds via coupling or radical processes. Such methods for direct C-H borylation reactions are of high synthetic value to reduce the number of synthetic steps and the amount of waste and to improve efficiency.
View Article and Find Full Text PDFMolecules
December 2024
Department of Pharmacy and Interuniversity Research Centre on Bioactive Peptides (CIRPeB), University of Naples "Federico II", Via Montesano 49, 80131 Naples, Italy.
Silver drugs have played a vital role in human healthcare for the treatment of infections for many centuries. Currently, due to antibiotic resistance, a potential scenario or the application of silver complexes may arise as substitutes for conventional antibiotics. In this perspective, N-heterocyclic carbene (NHC) ligands have been selected as carrier molecules for silver ions.
View Article and Find Full Text PDFJ Med Chem
January 2025
Sorbonne Université, CNRS Institut Parisien de Chimie Moléculaire, IPCM, F-75005 Paris, France.
Despite recent advances in cancer treatment, there is still a need for novel compounds with antineoplastic activity. Among 11 biphenyl-based organogold(III) -heterocyclic carbene (NHC) (BGC) complexes of general formula [(C^C)Au(NHC-pyr)X], where (C^C) = 4,4'-ditertbutylbiphenyl, X = Cl or phenylacetylide, and (NHC-pyr) is a pyridyl-substituted NHC ligand, the complex bearing a 4-CF-pyridyl substituent and a chloride ligand showed promising antineoplastic activity on the triple negative breast cancer cell line. was able to induce cell apoptosis but had no effect on the cell cycle.
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