Departamento de Química, Facultad de Ciencias, Módulo 13., Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049, Madrid, Spain.
Angew Chem Int Ed Engl. 2017 Jun 6;56(24):6788-6792. doi: 10.1002/anie.201701161. Epub 2017 May 10.
Owing to its versatility in synthetic chemistry, TPB (tris[2-diisopropylphospino)phenyl]borane) is a very important frustrated Lewis Pair. The unusual stability of the neutral radical (TPB)Cu has been related to the presence of a one-electron B-Cu bond. Herein we show, through the use of different computational chemistry methods, that the existence and nature of this kind of A⋅⋅⋅M bond (A=donor atom, M=transition metal) depends on the surrounding chemical structure, and can be genuine one-electron sigma bonds only if appropriate metal ligands (Y), able to trap the charge in the desired region, are chosen. This ability is modulated by the subtle balance between the electronegativity of the different atoms along the A⋅⋅⋅M⋅⋅⋅Y bond paths. Most importantly, contrary to many TPB complexes in which boron acts as a Lewis acid, in one-electron-bond-containing structures boron behaves as a Lewis base.
由于其在合成化学中的多功能性，TPB（三[2-二异丙基膦基]苯基]硼烷）是一种非常重要的受阻路易斯对。中性自由基（TPB）Cu 的异常稳定性与存在单电子 B-Cu 键有关。在此，我们通过使用不同的计算化学方法表明，这种 A⋅⋅⋅M 键（A=给体原子，M=过渡金属）的存在和性质取决于周围的化学结构，如果选择合适的金属配体（Y），能够在所需区域捕获电荷，则可以是真正的单电子 sigma 键。这种能力受沿 A⋅⋅⋅M⋅⋅⋅Y 键路径的不同原子的电负性之间的微妙平衡调节。最重要的是，与许多作为路易斯酸的硼的 TPB 配合物相反，在含有单电子键的结构中，硼表现为路易斯碱。
