Synthesis, Characterization, and Crystal Structure of Cyclotrisilene: A Three-Membered Ring Compound with a Si−Si Double Bond

Abstract

Red-orange crystals of cyclotrisilene 3 were obtained by the reaction of the dibromotrisilane 1 and the tribromodisilane 2 with sodium in toluene [Eq. (1)]. The X-ray crystal structure of 3 shows that the three-membered ring is almost an isosceles triangle and has a twisted Si-Si double bond with a length of 2.138(2) Å.

Isolable silylene, disilenes, trisilaallene, and related compounds

“…However, the reduction of 7 with pottasium graphite in THF at low temperature gave an isomeric cyclotrisilene 8 as the first cyclotrisilene (Scheme 3) [16]. Another cyclotrisilene was synthesized and analyzed by X-ray crystallography soon by Sekiguchi et al [17].…”

“…The reactions of stable cyclic dialkylgermylene 26 and dialkylstannylene 19 with 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO, R 0 2 NO Å ) radical (2 equiv) to give the corresponding 1:2 adducts 32 and 33, respectively (Eq. (17)). The kinetics of the stepwise addition of two TEMPO molecules to germylene 26 revealed that the initial addition of TEMPO to 26 was 10 10 times slower than the second TEMPO addition to the resulted germyl radical 32 [47b,51].…”

Si3S-, Si3Se-, Si3Te-Bicyclo[1.1.0]butanes and Si3S2-Bicyclo[1.1.1]pentane

“…We applied a novel approach for the preparation of target bicyclo[1.1.0]butanes, based on the [1 + 2] cycloaddition of elemental chalcogens across the highly reactive Si Si bond of trisilirene 1. 4 Accordingly, 2-thia-, 2-selena-, and 2-tellura-1,3,4-trisilabicyclo[1.1.0]butanes 2a-c were readily available in high yields by the straightforward reaction of 1 with an excess of propylene sulfide or one equivalent of elemental S in benzene, excess of elemental Se or Te in THF (Scheme 1). 5 All compounds were isolated as yellow or orange-yellow air-sensitive crystals and were fully characterized.…”

A Stable Bicyclic Compound with Two Si=Si Double Bonds

“…The geometry around the Si=Si bonds in 2 is not planar but substantially twisted; the dihedral angle Si2-Sil-Si6-Si7 (4) is 30.0(5)", and the sums of the bond angles are 358.9' at Sil and 358.0' at Si6, respectively. The Si=Si double bonds in 2 are 0.05 A longer, and the Si-Si single bonds in the three-membered ring are 0.03 to 0.04 A shorter, than the corresponding bonds in tees(&-tert-butyhethylsily1)cyclotrisilene 5 (8). The geometry of a model spiropentasiladiene 6 was optimized by ab initio molecular orbital (MO) calculations at the B3LYPl6-31G(d) level with the Gaussian 98 program (16, 17).…”