Crystal Structures of Tris(tert-butyl)boron, -aluminum, -gallium, and -indium: Nonplanarity of the AlC3 Skeleton and Evidence of Inter- and Intramolecular “Agostic” or Hyperconjugative Interactions
Crystal Structures of Tris(tert-butyl)boron, -aluminum, -gallium, and -indium: Nonplanarity of the AlC3 Skeleton and Evidence of Inter- and Intramolecular “Agostic” or Hyperconjugative Interactions
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三(叔丁基)硼、-铝、-镓和-铟的晶体结构：AlC3 骨架的非平面性以及分子间和分子内“无政府”或超共轭相互作用的证据
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
S. Parsons
中科院分区：
文献类型：
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作者：
A. Cowley;A. J. Downs;Sarah Marchant;Victoria A. Macrae;Russell A. Taylor;S. Parsons
在低温（150 ~ 220 K）下测定的硼、铝、镓和铟(M)的三（叔丁基）衍生物的x射线晶体结构显示，与相应的三甲基衍生物相比，这些三（叔丁基）衍生物的M - C键始终更长，基本上是单体分子单元。比较显示的三个结构显著改善,分子间M···β甲基绑定的顺序M = B∼Ga < < Al,导致明显的非平面的MC3骨架与上述0.25 M原子取代的平面第四纪C原子的情况下M =。倾斜的叔丁基组C M−债券,这是共同M = B或半岛时,似乎反映了分子内超共轭的影响或“agostic”键。
X-ray crystal structures determined at low temperatures (150−220 K) for the tris(tert-butyl) derivatives of boron, aluminum, gallium, and indium (M) reveal essentially monomeric molecular units throughout with consistently longer M−C bonds than in the corresponding monomeric trimethyl derivatives. Comparison of the three structures shows a significant strengthening of intermolecular M···β-CH3 binding in the order M = B ∼ Ga < In < Al, resulting in a distinctly nonplanar MC3 skeleton with the M atom displaced 0.25 A above the plane of the quaternary C atoms in the case where M = Al. Tilting of the tert-butyl groups about the M−C bonds, which is concerted when M = B or Al, appears to reflect the influence of intramolecular hyperconjugation or “agostic” bonding.