New Isolable Dialkylsilylene and Its Isolable Dimer That Equilibrate in Solution
New Isolable Dialkylsilylene and Its Isolable Dimer That Equilibrate in Solution
复制标题
DOI：
10.1021/ja310391m
复制
发表时间：
2012-12-12
影响因子：
15
通讯作者：
Iwamoto, Takeaki
中科院分区：
文献类型：
--
作者：
Abe, Takashi;Tanaka, Ryoji;Iwamoto, Takeaki
合成了含双齿烷基取代基的新型可分离二烷基硅烯3。硅烯3的再结晶得到黄色的3晶体和橙红色的四烷基二烯4晶体，3的二聚体。在固态中，3以单体的形式存在，在配位硅原子之间的距离最近，为6.745埃，而二烯4的Si=Si双键距离非常长，为2.252埃。通过核磁共振和紫外可见光谱观察到3和4在溶液中的平衡，并估计了平衡的热力学参数为δ H = -36 +/- 3 kJ mol（-1）和δ S = -170 +/- 15 kJ mol(-1) K-1。对二价硅周围空间需求的测量指标——埋藏体积百分比的分析表明，3和4的烷基取代基的柔性空间体积允许硅烯3可逆地二聚化为二烯4，并使两种物质分离。
The new isolable dialkylsilylene 3 bearing a bidentate alkyl substituent was synthesized. Recrystallization of silylene 3 gave yellow crystals of 3 and orange-red crystals of tetraalkyldisilene 4, a dimer of 3. In the solid state, 3 exists as a monomer with a closest distance of 6.745 angstrom between dicoordinate silicon atoms, while disilene 4 has a remarkably long Si=Si double bond distance of 2.252 angstrom. An equilibrium between 3 and 4 in solution was observed by NMR and UV-vis spectroscopies, and the thermodynamic parameters of the equilibrium were estimated to be Delta H = -36 +/- 3 kJ mol(-1) and Delta S = -170 +/- 15 J mol(-1) K-1. Analysis of the percent buried volume, a measure of the steric demand around the divalent silicon, showed that the flexible steric bulkiness of the alkyl substituent of 3 and 4 allows the reversible dimerization of silylene 3 to disilene 4 and the isolation of both species.