New zirconium complexes supported by N-heterocyclic carbene (NHC) ligands: Synthesis and assessment of hydroamination catalytic properties
| Autor: | Ana M. Martins, Rui F. Munhá, Sónia Barroso, Sara R. M. M. de Aguiar |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Zirconium
Chemistry Ligand Organic Chemistry chemistry.chemical_element Biochemistry Medicinal chemistry Catalysis Inorganic Chemistry Metal NMR spectra database chemistry.chemical_compound visual_art Octahedral molecular geometry Materials Chemistry visual_art.visual_art_medium Organic chemistry Hydroamination Physical and Theoretical Chemistry Carbene |
| Zdroj: | Journal of Organometallic Chemistry. 760:60-66 |
| ISSN: | 0022-328X |
| DOI: | 10.1016/j.jorganchem.2013.11.041 |
| Popis: | Reactions of 2-(bromomethyl)-4,6-di-tert-butylphenol or 2-(bromomethyl)-4,6-bis(2-phenylpropan-2-yl)phenol with 1H-imidazole led to syntheses of N,N-disubstituted imidazolium bromides presenting two methylene-bis(2,4-di-tert-butylphenol) ([H2L1]Br) or methylene-bis(2,4-di-tert-butylphenol) ([H2L2]Br) appended groups. Treatment of Zr(NMe2)4 with [H2L1]Br or [H2L2]Br gave tethered NHC zirconium complexes of general formula [ZrL(NMe2)(THF)Br] (L = L1, 7; L2, 8). The bonding of the tridentate ligands to the metal adopts S-shape conformation. In solution a fluxional process between the left- and right-handed forms of the ligand is observed for both complexes. In agreement with the NMR spectra, the optimised structure obtained by DFT revealed octahedral geometry around zirconium with mutually trans Br and Ccarbene donors. Complexes 7 and 8 react with 2,2-diphenylpent-4-en-1-amine in a 1:1 ratio to give the hydroamination product 2-methyl-4,4-diphenylpyrrolidine. In catalytic conditions, the systems deactivate and catalytic conversions are not observed. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect