An Isolable Radical Anion and Dianion of a Cyclotetrasilane: Synthesis and Structure of [Si{1,2‐(NEt)₂C₆H₄}]₄^−. and [Si{1,2‐(NEt)₂C₆H₄}]₄²⁻

Abstract

Silicon squares up: The silylene Si[1,2‐(NR)2C6H4] (R=CH2tBu) is thermally stable owing to its bulky substituent. What effect will a reduction of the size of R have on the stability of a two‐coordinate SiII species? Results show that a silylene with R=Et cannot be isolated but will yield a stable radical anion (see picture) and dianion of a cyclotetrasilane.

Compositional variations in monomeric trimethylsilylated allyl lanthanide complexes

“…Despite the ostensible use of the potassium salt of the [A 0 ] À anion, it is likely that the alkali metal in all three of the crystal structures of \½KðthfÞ 4 ½LnA 0 3 I" (Ln = Ce, Tb, Er) is mostly lithium. This is consistent both with typical coordination numbers for Li + and K + with THF (4 and 6, [21,22], respectively), and also with the M-O bond lengths (ca. [26].…”

Si‐, Ge‐, and Sn‐Centered Free Radicals: From Phantom Species toGrams‐Order‐Scale Materials

“…[26] This compound was formed, together with the more extensively reduced species, the cyclotetrasilane dianion 12, upon reduction of the heterocyclic dichlorosilane precursor 11 with metallic potassium in THF (Scheme 8).…”

Recent developments in the chemistry of stable silylenes

“…In this section, the reactivity of these species with or as radicals is surveyed. The only example of the radical chemistry of 3 appears to be the previously discussed cyclotetrasilane radical anion 6 ÀÅ [11].…”

“…EPR data obtained following electrochemical reduction of 1 show hfc to six nitrogen and three silicon atoms (g = 2.0035, a( 29 Si) = 25.77 G, a( 14 N) = 1.3 G) suggesting the existence of a cyclotrisilane anion radical (1 ÀÅ ) 3 (t 1/2 % 30 s at 20°C) rather than the simple radical anion 1 ÀÅ (Scheme 8). The higher steric demand of the tert-butyl group compared to the neo-pentyl group may prevent formation of a cyclotetrasilane analogous to 6 ÅÀ [11].…”