Expedient synthesis of NOxy-Heterocyclic Carbenes (NOHC) ligands and metal complexes using mechanochemistry

Wróblewska, Aneta; Lauriol, Gaëtan; Mlostoń, Grzegorz; Bantreil, Xavier; Lamaty, Frédéric

doi:10.1016/j.jorganchem.2021.121914

Cited by 12 publications

(6 citation statements)

References 62 publications

(66 reference statements)

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“…While much research has focused on classical NHCs with carbon-based substituents on the diaminoheterocycle nitrogen atoms, examples for NHCs with other N , N ′-substituents such as boron, , oxygen, phosphorus, − and hydrogen − have recently been described. (Figure ).…”

Section: Introductionmentioning

confidence: 99%

A Ruthenium Protic N-Heterocyclic Carbene Complex as a Precatalyst for the Efficient Transfer Hydrogenation of Aryl Ketones

et al. 2022

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A neutral azole precursor to a protic N-heterocyclic carbene (pNHC) ligand, 6-((4,5-diphenyl-1H-imidazol-1-yl)methyl)-2,2′-bipyridine (3), was prepared from 6-(bromomethyl)-2,2′-bipyridine (2) and 4,5-diphenylimidazole. Complex [RuCl-(pNHC-bpy)(PPh 3 ) 2 ](PF 6 ) (4) bearing a protic, bipyridinetethered NHC ligand was prepared by refluxing 3 with RuCl 2 (PPh 3 ) 3 and KPF 6 in methanol and was characterized by nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry, elemental analysis, and a single-crystal X-ray diffraction study. The hydrido complex [RuH(pNHC-bpy)(PPh 3 ) 2 ](PF 6 ) (5) was prepared by reaction of 4 with NaBH 4 in ethanol and characterized by NMR and Fourier transform infrared spectroscopy. Complex 5 was used as the catalyst (0.1 mol % loading) in the transfer hydrogenation of a range of alkyl/aryl ketones in basic iso-propanol at 60 °C. Bulky alkyl groups or ortho-substituted aryl groups at the ketones slowed down or inhibited the catalytic transformation. The addition of an excess of triphenylphosphine also slowed the catalysis, providing an indication for a mechanism involving phosphine dissociation, while the addition of an excess of elemental mercury had only a small effect on the conversion. The importance of potassium cations in the mechanism is consistent with the observation of reduced catalytic conversion when [2,2,2]-cryptand was present or when 1,8-diazabicyclo[5.4.0]undec-7-ene was used as the base. A plausible homogeneous catalysis mechanism involving the innersphere addition of hydride to the substrate in the transition state TS1 is supported by density functional theory calculations where the potassium ion has replaced the hydrogen atom of the N−H group in a protic NHC.

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Section: Introductionmentioning

confidence: 99%

A Ruthenium Protic N-Heterocyclic Carbene Complex as a Precatalyst for the Efficient Transfer Hydrogenation of Aryl Ketones

et al. 2022

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“…Having these good results in hand, our group developed, in collaboration with A. Wróblewska and G. Mlostoń, the mechanosynthesis of silver complexes bearing N-Oxy-Heterocyclic Carbenes (NOHC) ligands. [94] The imidazolium salts were synthe-sized by alkylation of 1-hydroxyimidazole-3-oxides obtained from a diketone, hydroxylamine and formaldehyde. Metalation with silver(I) oxide furnished different 1,3-di(alkyloxy)imidazole-2-ylidenes metal complexes, including one example of a cationic bis-NOHC silver complex 42.…”

Section: Discovery and Development Of Original Bioactive Scaffoldsmentioning

confidence: 99%

“…Having these good results in hand, our group developed, in collaboration with A. Wróblewska and G. Mlostoń, the mechanosynthesis of silver complexes bearing N –Oxy‐Heterocyclic Carbenes (NOHC) ligands [94] . The imidazolium salts were synthesized by alkylation of 1‐hydroxyimidazole‐3‐oxides obtained from a diketone, hydroxylamine and formaldehyde.…”

Section: Mechanosynthesis Of Biologically Active Coordination Complexesmentioning

confidence: 99%

Sustainable Mechanosynthesis of Biologically Active Molecules

et al. 2022

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Synthetic mechanochemistry, the use of mechanical force produced by milling, grinding or extruding, as an activation technique, provides access to chemical entities of all kinds. This Review is focused on examples reported so far of known Active Pharmaceutical Ingredients (APIs), and effectively evaluated bioactive molecules, all prepared by mechanosynthesis. Three families of molecules are discussed: heterocyclic compounds, metal complexes and peptides. Advantages of the mechanochemistry approach are highlighted especially from a green chemistry and efficacy point of view.

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“…Recently, however, they have emerged as powerful catalysts in their own right [11]. Unsurprisingly for coordination compounds of coinage metals [12][13][14][15], silver complexes (of course, including…”

Section: Introductionmentioning

confidence: 99%

A Fluoroponytailed NHC–Silver Complex Formed from Vinylimidazolium/AgNO3 under Aqueous–Ammoniacal Conditions

et al. 2022

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3-(1H,1H,2H,2H-Perfluorooctyl)-1-vinylimidazolium chloride [2126844–17–3], a strong fluorosurfactant with remarkably high solubility in water, was expediently converted into the respective doubly NHC-complexed silver salt with nitrate as counter ion in quantitative yield. Due to its vinyl substituents, [bis(3-(1H,1H,2H,2H-perfluorooctyl)-1-vinylimidazol-2-ylidene)silver(I)] nitrate, Ag(FNHC)2NO3, represents a polymerizable N-heterocyclic carbene transfer reagent, thus potentially offering simple and robust access to coordination polymers with crosslinking metal bridges. The compound was characterized by infrared and NMR spectroscopy, mass spectrometry as well as elemental analysis, and supplemented by X-ray single-crystal structure determination. It crystallizes in the monoclinic crystal system in the space group P21/c. With 173.3°, the geometry of the Ag-carbene bridge deviates slightly from linearity. The disordered perfluoroalkyl side chains exhibit a helical conformation.

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Expedient synthesis of NOxy-Heterocyclic Carbenes (NOHC) ligands and metal complexes using mechanochemistry

Cited by 12 publications

References 62 publications

A Ruthenium Protic N-Heterocyclic Carbene Complex as a Precatalyst for the Efficient Transfer Hydrogenation of Aryl Ketones

A Ruthenium Protic N-Heterocyclic Carbene Complex as a Precatalyst for the Efficient Transfer Hydrogenation of Aryl Ketones

Sustainable Mechanosynthesis of Biologically Active Molecules

A Fluoroponytailed NHC–Silver Complex Formed from Vinylimidazolium/AgNO3 under Aqueous–Ammoniacal Conditions

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