Solid-State NMR and DFT Studies on the Formation of Well-Defined Silica-Supported Tantallaaziridines: From Synthesis to Catalytic Application

• Published in: Chemistry : a European journal Vol. 22; no. 9; pp. 3000 - 3008
• Main Authors: Hamzaoui, Bilel, Pelletier, Jérémie D. A., Abou-Hamad, Edy, Chen, Yin, El Eter, Mohamed, Chermak, Edrisse, Cavallo, Luigi, Basset, Jean-Marie
• Format: Journal Article
• Language: English
• Published: WEINHEIM Blackwell Publishing Ltd 24.02.2016; Wiley; Wiley Subscription Services, Inc
• Subjects: Activation; Alkenes; Amines; Aromatic compounds; Catalysis; Catalysts; Chemical synthesis; Chemistry; Chemistry, Multidisciplinary; Formations; Fourier transforms; hydroamination; Infrared spectroscopy; Intermediates; Magnetic resonance spectroscopy; Mathematical analysis; metallacycles; NMR; NMR spectroscopy; Nuclear magnetic resonance; Physical Sciences; Science & Technology; Silica; Silicon dioxide; solid-state NMR spectroscopy; Spectroscopic analysis; Spectrum analysis; Substrates; supported catalysts; Tantalum; ZIRCONOCENE ETA-2-IMINE COMPLEXES; solid-state NMR spectroscopy; TANTALUM COMPLEXES; UNACTIVATED OLEFINS; supported catalysts; INTERMOLECULAR HYDROAMINOALKYLATION; DYNAMIC KINETIC RESOLUTION; hydroamination; ORDER REGULAR APPROXIMATION; CYCLIC CARBONATE; tantalum; DENSITY-FUNCTIONAL THEORY; GAUSSIAN-BASIS SETS; metallacycles; AMINO-ACID ESTERS
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201504439

Single‐site, well‐defined, silica‐supported tantallaaziridine intermediates [≡Si‐O‐Ta(η2‐NRCH2)(NMe2)2] [R=Me (2), Ph (3)] were prepared from silica‐supported tetrakis(dimethylamido)tantalum [≡Si‐O‐Ta(NMe2)4] (1) and fully characterized by FTIR spectroscopy, elemental analysis, and 1H,13C HETCOR and DQ TQ solid‐state (SS) NMR spectroscopy. The formation mechanism, by β‐H ion, was investigated by SS NMR spectroscopy and supported by DFT calculations. The C−H activation of the dimethylamide ligand is favored for R=Ph. The results from catalytic testing in the hydroaminoalkylation of alkenes were consistent with the N‐alkyl aryl amine substrates being more efficient than N‐dialkyl amines. Single‐site well‐defined silica‐supported tantallaaziridines [≡Si‐O‐Ta(η2‐NRCH2)(NMe2)2] (R=Me, Ph) were isolated and fully characterized. The formation mechanism by β‐H ion was investigated by solid‐state NMR spectroscopy and supported by DFT calculations. Catalytic testing for the hydroaminoalkylations of alkenes were consistent with the N‐alkyl‐arylamine substrates being more efficient than N‐dialkylamines (see scheme).