| Title: | Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry |
| Author(s): | Aljuhani MA; Pelletier JDA; Basset JM; |
| Address: | "KAUST Catalysis Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST). KAUST Catalysis Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST); jeremie.pelletier@kaust.edu.sa" |
| ISSN/ISBN: | 1940-087X (Electronic) 1940-087X (Linking) |
| Abstract: | "With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [( identical withSi-O-)Hf(=NMe)(eta(1)-NMe2)] is designed and prepared according to the methodology developed by surface organometallic chemistry (SOMC). In this framework, catalytic cycles can be determined by isolating crucial intermediates. All air-sensitive materials are handled under inert atmosphere (using gloveboxes or a Schlenk line) or high vacuum lines (HVLs, <10(-5) mbar). The preparation of SiO2-700 (silica dehydroxylated at 700 degrees C) and subsequent applications (the grafting of complexes and catalytic runs) requires the use of HVLs and double-Schlenk techniques. Several well-known characterization methods are used, such as Fourier-transform infrared spectroscopy (FTIR), elemental microanalysis, solid-state nuclear magnetic resonance spectroscopy (SSNMR), and state-of-the-art dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP-SENS). FTIR and elemental microanalysis permit scientists to establish the grafting and its stoichiometry. (1)H and (13)C SSNMR allows the structural determination of the hydrocarbon ligands coordination sphere. DNP SENS is an emerging powerful technique in solid characterization for the detection of poorly sensitive nuclei ((15)N, in our case). SiO2-700 is treated with about one equivalent of the metal precursor compared to the amount of surface silanol (0.30 mmol.g(-1)) in pentane at room temperature. Then, volatiles are removed, and the powder samples are dried under dynamic high vacuum to afford the desired materials [( identical withSi-O-)Hf(eta(2)pi-MeNCH2)(eta(1)-NMe2)(eta(1)-HNMe2)]. After a thermal treatment under high vacuum, the grafted complex is converted into metal imido silica complex [( identical withSi-O-)Hf(=NMe)(eta(1)-NMe2)]. [( identical withSi-O-)Hf(=NMe)(eta(1)-NMe2)] effectively promotes the metathesis of imines, using the combination of two imine substrates, N-(4-phenylbenzylidene)benzylamine, or N-(4-fluorobenzylidene)-4-fluoroaniline, with N-benzylidenetert-butylamine as substrates. A significantly lower conversion is observed with the blank runs; thus, the presence of the imido group in [( identical withSi-O-)Hf(=NMe)(eta(1)-NMe2)] is correlated to the catalytic performance" |
| Keywords: | "Catalysis Chemistry, Organic/*methods Hydroxylation Imines/*chemistry Ligands Magnetic Resonance Spectroscopy Organometallic Compounds/*chemistry Silicon Dioxide/*chemistry Solvents/chemistry Spectroscopy, Fourier Transform Infrared Vacuum;" |
| Notes: | "MedlineAljuhani, Maha A Pelletier, Jeremie D A Basset, Jean-Marie eng Research Support, Non-U.S. Gov't Video-Audio Media 2019/11/05 J Vis Exp. 2019 Oct 18; (152). doi: 10.3791/59409" |
