RESUMEN
The aluminium salt [(NHC)Al(tol)(C6F5)2][B(C6F5)4], (NHC = C3H2(N(iPr2C6H3))2) is shown to behave as a Lewis superacid as it abstracts fluoride from [SbF6]-. It also acts as a Lewis acid catalyst for hydrosilyation, hydrodefluorination and Friedel-Crafts reactions.
RESUMEN
The aluminum analogue of Piers' borane, [HAl(C6F5)2]31, is prepared on a gram-scale. Density functional theory (DFT) calculations reveal 1 has a higher fluoride ion affinity (FIA) than Piers' borane, while the Al-H moiety proved to be a strong hydride donor, reacting with alcohol and terminal alkyne to give the corresponding dehydrogenative products 3 and 4. Hydroalumination product 5 was prepared via reaction of 1 with aldehyde. In addition, 1 catalyzes the hydrosilylation of alkynes and alkenes.
RESUMEN
We report herein a facile and highly modular access to an intriguing class of free Au-substituted phosphines (AuPhos), namely (LAu)n PR3-n (L=singlet carbene ligand; R=H, aryl, alkyl, silyl) (n=1-3). The Tolman electronic parameter (TEP) values coupled with theoretical investigations showcase that Au-substitution can boost the electron-releasing ability of AuPhos, thus leading to an electronically and sterically tunable, extremely electron-rich phosphorus center. The high basicity of AuPhos is attributed to the d-p lone pair π-repulsion arising from interaction between Au substituents and the lone pair at P. A series of multi-nuclear transition metal complexes (i.e. Rh, Ir, Pd, Au, W, Mn) ligated by AuPhos are readily prepared via a straightforward process. Preliminary catalytic results reveal the facilitation of Pd-catalyzed C-N coupling reactions and Ir-catalyzed decarbonylation reactions via AuPhos. This work provides insights for future development of electron-rich ligands.