Horn Julian, Widera Anna, Litters Sebastian, Kaifer Elisabeth, Himmel Hans-Jörg
Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany.
Dalton Trans. 2018 Feb 6;47(6):2009-2017. doi: 10.1039/c7dt04433j.
Diborane(4) compounds are versatile reagents in synthetic chemistry. Generally, diboranes(4) with sp-hybridized boron atoms react as electrophiles. By contrast, the chemistry of nucleophilic diborane(4) compounds with two sp-hybridized boron atoms is very much underdeveloped. In this work, we systematically vary the substituents of electron-rich diborane(4) compounds with bridging guanidinate substituents. In this way, five new diboranes are synthesized and fully characterized. Using quantum chemical computations, we show that the electronic properties and reactivity of these compounds can be rationally varied by the choice of substituents. The HOMO energies, adiabatic ionization energies and proton affinities are considered as parameters to compare the chemical properties of these unusual compounds.
二硼烷（4）化合物是合成化学中用途广泛的试剂。一般来说，具有sp杂化硼原子的二硼烷（4）作为亲电试剂发生反应。相比之下，具有两个sp杂化硼原子的亲核二硼烷（4）化合物的化学性质研究得还很不充分。在这项工作中，我们系统地改变了带有桥连胍基取代基的富电子二硼烷（4）化合物的取代基。通过这种方式，合成并全面表征了五种新的二硼烷。利用量子化学计算，我们表明这些化合物的电子性质和反应活性可以通过取代基的选择合理地改变。最高占据分子轨道（HOMO）能量、绝热电离能和质子亲和能被视为比较这些特殊化合物化学性质的参数。
