Dihydrogen Activation with a Neutral, Intermolecular Silicon(IV)‐Amine Frustrated Lewis Pair

Abstract

The heterolytic cleavage of dihydrogen constitutes the hallmark reaction of frustrated Lewis pairs (FLP). While being well‐established for planar Lewis acids, such as boranes or silylium ions, the observation of the primary H2 splitting products with non‐planar Lewis acid FLPs remained elusive. In the present work, we report bis(perfluoro‐N‐phenyl‐ortho‐amidophenolato)silane and its application in dihydrogen activation to a fully characterized hydridosilicate. The strict design of the Lewis acid, the limited selection of the Lewis base, and the distinct reaction conditions emphasize the narrow tolerance to achieve this fascinating process with a tetrahedral Lewis acid.

Silicon Catalyzed C−O Bond Ring Closing Metathesis of Polyethers

“…Bis(perfluoro‐ N ‐phenylamido phenolato)silane 2 (Figure 1 d), a Lewis acid developed recently in our lab for the FLP type dihydrogen activation, was employed. [20] This Lewis acid is similarly Lewis acidic as 1 , but even less biased for bidentate substrate binding (Figure 3 ). Indeed, 2 exhibits a remarkably improved performance in the degradation of diglyme (3 mol%, 81 %), outperforming all previous results (cf.…”

Catalytic Degradation of Aliphatic Ethers using the Lewis Superacidic Bis(perfluoropinacolato)silane

“…For this reason, catalysts with two or three potential coordination sites for multidentate substrates were found less active for the ring‐closing metathesis, whereas catalysts with blocked or less favorable multiple‐coordination sites showed increased activity. This was underpinned by an experiment with bis(perfluoro‐ N ‐phenylamidophenolato)silane, [15] where the double coordination of diglyme is even less stabilized as for [Si(cat Cl ) 2 ] n [12] . Following this reasoning, we expected that our pinacolato silane 1 ⋅ MeCN shows even higher reactivity as acetonitrile should be exchanged in solution with the employed etheric substrate (Scheme 1) Furthermore, the liberated silane 1 possesses a similar Lewis acidity compared to [Si(cat Cl ) 2 ] n in case of fluoride ion affinity calculations (FIA: 474 kJ mol −1 ( 1 ) vs. 507 kJ mol −1 ) as well as GB measurements (Δδ( 31 P)=35.8 ppm ( 1 ) vs. 35 ppm) [13,14e] .…”

Bis(amidophenolato)phosphonium: Si−H Hydride Abstraction and Phosphorus‐Ligand Cooperative Activation of C−C Multiple Bonds

“…The aminophenoles 1 a and 1 b were prepared by literature‐known procedures and are accessible within one or two high‐yielding steps at a multigram scale (Figure 2). [7,9] Fully fluorinated 1 c was recently introduced as a ligand for the preparation of a highly Lewis acidic silane and is easily prepared via a three‐step procedure starting from hexafluorobenzene [10] . Reacting the aminophenols with PCl 5 proceeded with the liberation of HCl and yielded the respective bis(amidophenolato)chlorophosphoranes 2 a – c in good to excellent yields after workup [11]…”

“…[7,9] Fully fluorinated 1 c was recently introduced as a ligand for the preparation of a highly Lewis acidic silane and is easily prepared via a three-step procedure starting from hexafluorobenzene. [10] Reacting the aminophenols with PCl 5 proceeded with the liberation of HCl and yielded the respective bis(amidophenolato)chlorophosphoranes 2 a-c in good to excellent yields after workup. [11] While the reaction with 1 c occurred readily at room temperature, more forcing conditions were required with 1 a/b.…”