The (Me ₅ C ₅ )Si ⁺ Cation: A Stable Derivative of HSi ⁺

Abstract

The reaction of decamethylsilicocene, (Me5C5)2Si, with the proton-transfer reagent Me5C5H2+B(C6F5)4- produces the salt (Me5C5)Si+ B(C6F5)4(2), which can be isolated as a colorless solid that is stable in the absence of air and moisture. The crystal structure reveals the presence of a cationic pi complex with an eta5-pentamethylcyclopentadienyl ligand bound to a bare silicon center. The 29Si nuclear magnetic resonance at very high field (delta = - 400.2 parts per million) is typical of a pi complex of divalent silicon. The (eta5-Me5C5)Si+ cation in 2 can be regarded as the "resting state" of a silyliumylidene-type (eta1-Me5C5)Si+ cation. The availability of 2 opens new synthetic avenues in organosilicon chemistry. For example, 2 reacted with lithium bis(trimethylsilyl)amide to give the disilene E-[(eta1-Me5C5)[N(SiMe3)2]Si]2(3).

Recent Advances in Silylene Chemistry: Small Molecule Activation En-Route Towards Metal-Free Catalysis

“…The two silylene ligands are orientated in an orthogonal manner relative to each other, which is likely due to the steric strain associated with the SiMe 3 groups. Of particular interest in this report is the ability of complex 92 to activate H 2 at ambient conditions affording a bis(hydrosilyl)palladium complex (93) in high yield (84%) (Scheme 29). Complex 93 is remarkable in that it is the first example of a 12 valence electron Pd complex and that it exhibits a bent geometry around the Pd centre.…”

A Tamed Reactive Intermediate

“…Arguments over what exactly happens to demons and the environment as the entropy of the gas decreases in apparent violation of the Second Law have helped sharpen our understanding of the crucial concepts of measurement and information. One can attribute to Leo Szilard the discovery of the bit, the unit of information, as part of his 1929 Maxwell's demon paper (5).…”

“…No previous doubly charged ion of a nonmetal has been reported, except in highly coordinated forms such as R 3 Ge: 2+ (3). Singly charged, monocoordinated silicon, germanium, and tin cations exist, which are analogs of RC: + (4,5).…”

[2,6‐(Trip)2H3C6](Cp*)Si, eine stabile monomere Arylsilicium(II)‐ Verbindung

“…À (1), [16] Umsetzung von 1 mit dem Lithiumsalz LiAr*·Et 2 O (2; Ar* = 2,6-Trip 2 C 6 H 3 ) [18] in Hexan bei À80 8C lieferte das Salz LiB(C 6 F 5 ) 4 Bei der Verbindung handelt es sich um eine monomere Silicium(II)-Spezies mit einem h 3 -gebundenen Cp*-Liganden, einer s-gebundenen Arylgruppe und nichtkristallographischer Spiegelsymmetrie in der zentralen Einheit. Die Geometrie am Siliciumatom kann qualitativ auf der Basis einer sp 2 -Hybridisierung beschrieben werden (Rechnungen werden weiter unten vorgestellt), wobei ein Hybridorbital das freie Elektronenpaar enthält und die restlichen in die Bindungen zu den Substituenten eingebunden sind.…”