Structure and Reactions of an Isolable Ge=Si Doubly Bonded Compound, Tetra(t-butyldimethylsilyl)germasilene

Abstract

Tetra(t-butyldimethylsilyl)germasilene (8b) was synthesized using di(t-butyldimethylsilyl)hydridogermyllithium prepared by the germa-metallation of the corresponding dihydridogermane. Tetrasilylgermasilene 8b was obtained as single crystals by recrystallization from hexane at room temperature. The molecular structure of 8b is similar to those of the corresponding disilene 8a and digermene 8c but with an intermediate unsaturated bond length and twist angle between those of 8a and 8c. The reactions of 8b with methanol and 2,3-dimethylbutadiene gave the corresponding adducts. Equilibrium between 8b and the corresponding (trisilylsilyl)(silyl)germylene is suggested by the reaction of 8b with triethylsilane giving the germylene insertion product into the Si-H bond.

Cyclic Disilylated and Digermylated Germylenes

“…22 In addition, 29 Si NMR chemical shift calculations at the MP2/GIAO level predict for the silagermene (Me 3 Si) 2 Ge=Si(SiMe 3 ) 2 a silicon NMR chemical shift of δ( 29 Si) 158 ppm, which is very close to the experimentally observed values of persilylated silagermenes. 22,23 The tricyclic compound 5 also exhibits an interesting 29 Si NMR spectrum with two resonances at −69.7 and −94.1 ppm. While 4-fold silylated silicon atoms typically resonate around −130 ppm, the incorporation of such units into cyclotetrasilanes is accompanied by a downfield shift of some 40 ppm.…”

A Mixed Heavier Si=Ge Analogue of a Vinyl Anion

“…Besides, additional intense absorption bands are present at λ =413 nm ( ϵ =5470 L mol −1 cm −1 ) for 3 ⋅K(THF) and at λ max =417 nm ( ϵ =6130 L mol −1 cm −1 ) for 3 ⋅K(18‐c‐6). Two similar UV/Vis absorption bands were observed for a silagermene [( t BuMe 2 Si) 2 Si=Ge(SiMe 2 t Bu) 2 ] [ λ max =413 nm ( ϵ =5000 L mol −1 cm −1 ), 359 nm ( ϵ =2000 L mol −1 cm −1 )] [5e] …”

Bonding and structure of disilenes and related unsaturated group-14 element compounds

“…8a)) In Table 1 are summarized the UV-vis absorption spectra of acyclic tetrasilyldimetallenes 1a – 1f and related dimetallenes at room temperature in a hydrocarbon solvent. Interesting spectral features of tetrasilyldimetallenes are found in the table: (1) Whereas these tetrasilyldisilenes have no aromatic substituents, the longest absorption maxima are found at a wavelength longer than 400 nm.…”