Motomatsu Daiki, Ishida Shintaro, Ohno Koichi, Iwamoto Takeaki
Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki-aza-aoba, Aoba-ku, Sendai 980-8578 (Japan), Fax: (+81) 22-795-6558.
Chemistry. 2014 Jul 21;20(30):9424-30. doi: 10.1002/chem.201402868. Epub 2014 Jul 1.
A new 2,3-disila-1,3-butadiene (3) was synthesized as pale yellow crystals by a double sila-Peterson reaction of 1,1,2,2-tetrasilyl-1,2-dilithiodisilane with two equivalents of 2-adamantanone at 0 °C. In the solid state, the two Si=C bonds adopt a synclinal conformation with a dihedral angle of 76.8(1)°. UV/Vis spectra show two distinct absorption bands, assignable to the π(Si=C)→π*(Si=C) transition, at 371 and 322 nm and the former is considerably redshifted compared with that of structurally similar silenes. The 2,3-disilabutadiene isomerizes to the corresponding 1,3-disilabicyclo[1.1.0]butane with the activation parameters of ΔH(≠) = 74.5±5.4 kJ mol(-1) and ΔS(≠) = -71.1±17.1 J mol(-1) K(-1). DFT studies suggest that the isomerization proceeds through a conrotatory route rather than a disrotatory route. H2O and 9,10-phenanthrenequinone added across each Si=C bond in the 2,3-disila-1,3-butadiene. The UV/Vis spectrum and reactivity of 3 suggest that the interaction between the two Si=C bonds in 3 would be significant but rather small compared with that between Si=Si bonds in a synclinal tetrasilabutadiene.
通过1,1,2,2-四硅基-1,2-二锂二硅烷与两当量的2-金刚烷酮在0 °C下进行双硅基-彼得森反应，合成了一种新的2,3-二硅基-1,3-丁二烯（3），为浅黄色晶体。在固态中，两个Si=C键采取顺错构象，二面角为76.8(1)°。紫外/可见光谱显示在371和322 nm处有两个不同的吸收带，可归因于π(Si=C)→π*(Si=C)跃迁，与结构相似的硅烯相比，前者有相当大的红移。2,3-二硅基丁二烯异构化为相应的1,3-二硅基双环[1.1.0]丁烷，活化参数为ΔH(≠) = 74.5±5.4 kJ mol(-1)和ΔS(≠) = -71.1±17.1 J mol(-1) K(-1)。密度泛函理论研究表明，异构化通过顺旋途径而非对旋途径进行。水和9,10-菲醌加成到2,3-二硅基-1,3-丁二烯的每个Si=C键上。3的紫外/可见光谱和反应性表明，3中两个Si=C键之间的相互作用是显著的，但与顺错四硅基丁二烯中Si=Si键之间的相互作用相比相当小。
