Synthesis and characterization of chiral bidentate bis(N-heterocyclic carbene)-carboxylate palladium and nickel complexes
Complexes [Pd{(S)-NHCMes,R}2] (R = Me, 2a; iPr, 2b; iBu, 2c) and [Pd{(R)-NHCMes,Me}2] (2a’) were prepared by reaction of the corresponding imidazolium precursor [ImMes,R] (namely (S)–2-alkyl(3-mesityl-1H-imidazol-3- ium-1-yl)acetate, 1a-c, and (R)-2-methyl(3-mesityl-1H-imidazol-3-ium-1-yl)acetate, 1...
| Autores: | , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2022 |
| País: | España |
| Institución: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:idus.us.es:11441/139386 |
| Acceso en línea: | https://hdl.handle.net/11441/139386 https://doi.org/10.1016/j.ica.2022.120946 |
| Access Level: | acceso abierto |
| Palabra clave: | NHC-carboxylate Chiral Palladium Nickel X-ray |
| Sumario: | Complexes [Pd{(S)-NHCMes,R}2] (R = Me, 2a; iPr, 2b; iBu, 2c) and [Pd{(R)-NHCMes,Me}2] (2a’) were prepared by reaction of the corresponding imidazolium precursor [ImMes,R] (namely (S)–2-alkyl(3-mesityl-1H-imidazol-3- ium-1-yl)acetate, 1a-c, and (R)-2-methyl(3-mesityl-1H-imidazol-3-ium-1-yl)acetate, 1a’), with Ag2O and sub- sequent interaction with Pd(OAc)2, under appropriate conditions. Alternatively, complexes 2 were also obtained by treating compounds [ImMes,R], 1, with an in-situ prepared lithium diisopropylamide solution and then reaction with [Pd(OAc)2]. On the other hand, the nickel complex [Ni{(S)-NHCMes,iPr}2], 3b, was synthesized by the interaction of the complex [NiCp2] (Cp = η5-C5H5) with [ImMes,iPr], 1b, in THF. If this reaction was carried out in acetonitrile, a mixture of complex 3b and the cyclopentadienyl monocarbene complex [NiCp{(S)-NHCMes,iPr}], 4b, was obtained. Similarly to 2b, compound 3b was also prepared by the in-situ formation of the carbene [(S)– NHCMes,iPr]- and then reaction with [NiBr2(dme)] (dme = 1,2-dimethoxyethane). Complexes 2, 3 and 4 were obtained with good yields and fully characterized by analytical (HR-ESI and microanalysis), spectroscopic (IR, 1H and 13C NMR and polarimetry) and X-ray methods (2c). In the solid state, 2c is a square planar complex con- taining two [(S)-NHCMes,iBu]- ligands coordinated in a κ2-C,O fashion, where the carbene and carboxylate donors have the expected trans configuration. The existence of two possible conformers of complexes 2 and 3 was analyzed using DFT methods. |
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