1. Annulated 1,4-Disilabenzene-1,4-diide and Dihydrogen Splitting.
- Author
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Ebeler F, Vishnevskiy YV, Neumann B, Stammler HG, Szczepanik DW, and Ghadwal RS
- Abstract
The isolation of silicon analogues of phenyl anions such as (C
6 H5 )- and (C6 H4 )2- is challenging owing to their extremely high reactivity associated with their silylene character and weak C-Si π-interaction. Herein, we report the first annulated 1,4-disilabenzene-1,4-diide compound [(ADC)Si]2 ( 5 ) based on anionic dicarbene (ADC) scaffolds (ADC = PhC{N(Dipp)C}2 ; Dipp = 2,6- i Pr2 C6 H3 ) as a green-yellow crystalline solid. Compound 5 is prepared by KC8 reduction of the Si(IV) chloride [(ADC)SiCl3 ]2 ( 3 ) or the cyclic bis-chlorosilylene [(ADC)SiCl]2 ( 4 ), which are also prepared for the first time. 5 is a neutral molecule, and each of the two-coordinated Si(I) atoms has a lone pair and an unpaired electron. Experimental and theoretical data indicate delocalization of the silicon unpaired electrons, resulting in a 6π-electron C4 Si2 ring in 5 . The diradical character ( y ) for 5 amounts to 15%. At room temperature, 5 readily reacts with dihydrogen (H2 ) to form the elusive bis-hydridosilylenes [(ADC)SiH]2 ( Z )- 6 and ( E )- 6 . The [4 + 2]-cycloaddition of 5 and PhC≡CPh in yielding the barrelene-type bis-silylene [(ADC)SiCPh]2 ( 7 ) emphasizes the diradical reactivity of 5 . With elemental sulfur, 5 results in the S2 - and S3 -bridged silathione derivatives [(ADC)Si(S)]2 (μ-S2 ) ( 8a ) and [(ADC)Si(S)]2 (μ-S3 ) ( 8b ). Moreover, the treatment of 5 with Fe2 (CO)9 affords the Fe(0) complex [(ADC)Si(Fe(CO)4 )]2 (μ-CO) ( 9 ), in which each silicon atom serves as a two-electron σ-donor ligand and shares one electron with the bridging CO unit to form two Si-C bonds. The molecular structures of all compounds have been established by X-ray diffraction, and representative compounds have been analyzed by quantum chemical calculations.- Published
- 2024
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