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

Single-site, well-defined, silica-supported tantallaaziridine intermediates [Si-O-Ta((2)-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 H-1,C-13 HETCOR and DQ TQ solid-state (SS) NMR spectroscopy. The formation mechanism, by -H abstraction, 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.