Reactions of a bis-silylene (LSi-SiL, L = PhC(N t Bu)2) and a heteroleptic chloro silylene (LSiCl) with Benzil: Formation of bis(siladioxolene) and monosiladioxolene analogue with five-coordinate silicon atoms in both ring systems

Article abstract of DOI:10.1021/om100581u

LSi-SiL (L = PhC(NtBu)₂) (4) was reacted with benzil in toluene at room temperature to afford a compound that contains two siladioxolene rings connected by a Si-Si bond. This is the first reactivity study of 4 where the central Si-Si bond was not cleaved during the reaction. Furthermore, LSiCl (L = PhC(NtBu)₂) (6) was treated with benzil at ambient temperature in toluene to yield 2,5-dioxa-1-silacyclopent-3-ene (7). Both 5 and 7 were characterized by single-crystal X-ray diffraction and additionally by NMR spectroscopy, EI-MS spectrometry, and elemental analysis. Investigation of the molecular structure shows that the Si-Si bond length in 5 is 2.36 A, which is more than 2% shorter than the Si-Si bond length in 4. The formal oxidation state of silicon in 5 is +3, which is in agreement with its structure. The existence of 5 and 7 as stable compounds indicates that siladioxolenes can be electronically stabilized by ?-donor ligands.