Bis(perchlorocatecholato)silan – eine neutrale Silicium‐Lewis‐Supersäure

Abstract

Bisher sind noch keine neutralen Silicium-Lewis-Supersäuren bekannt. Wirberichtenhier über die Synthese des Bis(perchlorocatecholato)silans und bestätigen dessen Lewis-Superaziditätd urchB erechnungen (DLPNO-CCSD(T)) und Experimente (Fluoridabstraktion von SbF 6 À

Exploring the Lewis Acidity and Reactivity of Neutral Pentacoordinate Dithienophospholes

“…Compound 4 (331 kJ mol −1 ) has the highest FIA out of this series, followed by 6 (326 kJ mol −1 ), 2 d (299 kJ mol −1 ), 2 c (290 kJ mol −1 ), 2 b (285 kJ mol −1 ), and 2 a (272 kJ mol −1 ). Overall, these values qualify the new pentacoordinate P‐species as moderate Lewis acids [4b,22] . The previously reported pentacoordinate dithienophospholes have FIA values of 306–381 kJ mol −1 , where the lowest value corresponds to the most electron‐rich system, IVb (Ph, phenanthrene quinone) and the highest value is attributed to the most electron‐poor species, IVc (C 6 F 5 , o ‐chloranil).…”

Al(OCArF3)3 – a thermally stable Lewis superacid

“…Sundermeyer and Krossing et al described the extremely sensitive Lewis superacid Al(N(C 6 F 5 ) 2 ) 3 with a high FIA of 555 kJ mol –1 13. Only recently the group of Greb published a neutral silicon Lewis superacid14 and a review article on Lewis superacidity 15…”

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

“…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] . Deactivating effects caused by twofold coordination of the substrate should be sufficiently diminished by steric protection of the perfluoropinacolato groups.…”