Synthesis and characterization of oxygen-functionalized-NHC silver(I) complexes and NHC transmetallation to nickel(II).

Sophie Hameury (1) , Pierre de Frémont (1) , Pierre-Alain Breuil (2) , Hélène Olivier-Bourbigou (2) , Pierre Braunstein (1)

1 Institut de Chimie de Strasbourg
2 IFPEN - IFP Energies nouvelles

The new oxygen-functionalized-NHC silver(I) complexes bis(l-{2,6-diisopropylphenyl)-3-(2-hydroxyethyl)-1H-imidazol-2(3H)-ylidene)silver(I) chloride ([Ag{lmDiPP(EtOH)}2]CI, 4), bis(1-(2-hydroxyethyl)-3-mesityl-1H-imidazol-2(3H)-ylidene )silver(I) chloride ([Ag {lmMes(EtOH) }2]CI, 5),bis(l-(2-hydroxyethyl)-3-methyl-1H-imidazol-2(3H)-ylidene )silvet{l) chloride ([Ag { lmMe(EtOH) }2]Cl, 6), bis( l-(2,6-diisopropylphenyl)-3 -(2-hydroxyethyl)-1 H-imidazol-2(3H)-ylidene)silver(I) tetrafluoroborate ([Ag {ImDiPP(EtOH) }2]BF 4, 9) and bis( l-{2,6-diisopropylphenyl)-3-(2-methoxyethyl)IH-imidazol-2(3H)-ylidene)silver(I) chloride ([Ag{ImDiPP(EtOMe)}2]CI, 13), have been synthesized and fully characterized by NMR spectroscopy and single crystal X-ray diffraction. For some complexes, an uncommon heteronuclear coupling of 4J{'071109 Ag-1H) was unveiled. Their transmetallation ability was assessed in presence of different nickel(II) sources and the bis-NHC Ni{Il) complex bis( 1-(2,6-diisopropylphenyl )-3 -(2-methoxyethyl)-1 H-imidazol-2(3H)-ylidene )nickel{ll) chloride ([NiC12{ImDiPP(Et0Me)} 2], 15) was obtained from 13 and shown by X-ray diffraction to have a transarrangement of the two NHC ligands. In contrast, it was found with the other Ag{I) NHC complexes that the acidity of the alcohol OH proton was detrimental for the transmetallation process, and reprotonation of the CNHc carbon to give the corresponding imidazolium salt was observed.

Domaines: Polymères

Sophie Hameury, Pierre de Frémont, Pierre-Alain Breuil, Hélène Olivier-Bourbigou, Pierre Braunstein. Synthesis and characterization of oxygen-functionalized-NHC silver(I) complexes and NHC transmetallation to nickel(II).. Dalton Transactions, 2014, 43 (12), pp.4700-4710. ⟨10.1039/c3dt52773e⟩. ⟨hal-01071718⟩