A Tetrasilicon Analogue of Bicyclo[1.1.0]but‐1(3)‐ene Containing a Si=Si Double Bond with an Inverted Geometry

Abstract

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Silicon–silicon π single bond

“…The distance between the bridgehead silicon atoms is 2.853(1) Å. This value is far larger than the longest silicon-silicon σ bonds (2.697 Å 24 28,29 . The Si(1)-Si(2) bond length (2.3090(7) Å) is shorter than normal silicon-silicon bonds (2.358 Å) 30 , probably due to the connection of the two bridgehead silicon atoms.…”

Bonding Relationship between Silicon and Germanium with Group 13 and Heavier Elements of Groups 14–16

“…[8c] In digermavinylidene (33), the four atoms that defined the B 2 GeGe unit, lied within a single plane. The structural analysis of 33 revealed the presence of weak interaction between flanking arene π systems (aryl rings of each of the boryl ligands) and vacant in-plan p orbital at Ge2, confirmed by variable-temper- 2.167(2) C SIdipp À Si2À Si1: 97.6(1)° [16] 2.4716(11) Si2À Si1À Si2*: 115.09(3)° [24] 2.223 17B1À Si1À Si2: 127.34 14°, B2À Si2À Si1: 128.20 14° [ 27] Scheme 13. General synthetic methods for digermene: a) photolysis or ring opening of cyclotrigermanes, [31,32a] b) reductive dehalogenation [31,32b-d] and c) dimerization.…”

“…[23h-j] Recently, Iwamoto and Ishida et al synthesized a tetrasilicon compound (18), analogue of bicyclo [1.1.0]but-1(3)-ene, having a formal double bond between bridgehead silicon atoms. [24] The reduction of 1-chloro-1-(trichlorosilyl)silacyclopentane (17) with potassium graphite yielded 18 along with trisilaallene (19) as a by-product (Scheme 9a). The synthesis of 19 was previously reported by Kira and co-workers, [25] but with different alkyl substituents (SiMe 3 group instead of Si i PrMe 2 ).…”

“…The reduction of (boryl)trichlorosilane (24) with potassium graphite gave bridged alkoxy alkyl bis(disilenide) (25) by the cleavage of a THF molecule (Scheme 11b). The mechanism for the formation of 25 was explained as: first the reduction of 24 with potassium graphite generated the unstable bis(boryl) disilyne radical anion [(boryl)Si=Si(boryl)] À , which could cleave a THF molecule to form the alkoxy disilenide radical (boryl)K(THF) Si=Si(boryl)[O(CH 2 ) 4 ].…”

“…Recently, Iwamoto and Ishida et al . synthesized a tetrasilicon compound ( 18 ), analogue of bicyclo [1.1.0]but‐1(3)‐ene, having a formal double bond between bridgehead silicon atoms [24] . The reduction of 1‐chloro‐1‐(trichlorosilyl)silacyclopentane ( 17 ) with potassium graphite yielded 18 along with trisilaallene ( 19) as a by‐product (Scheme 9a).…”