Das Prasenjit, Patra Shanti Gopal, Chattaraj Pratim Kumar
Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
Phys Chem Chem Phys. 2022 Sep 28;24(37):22634-22644. doi: 10.1039/d2cp03532d.
Herein, we report for the first time the presence of a planar hexacoordinate boron (phB) atom in the global minimum energy structure of a neutral cluster system. The potential energy surface (PES) has been explored for CBAl systems using density functional theory (DFT). The global minima of CBAl (1a) and CBAl (1b) contain a phB center. However, the global minimum of CBAl (1c) does not have a phB atom. The CCSD(T)/aug-cc-pVTZ level of theory has been applied to compute the relative energies of the low-lying isomers with respect to the 1a and 1b structures of CBAl and CBAl systems, respectively. The exploration of the PES of CB systems indicates that the global minima do not contain a phB atom. However, the incorporation of an aluminium (Al) atom into the CB moiety produces structures containing a phB center in the CBAl systems. Hence, the Al metal has an important role in attaining a planar geometry having a hexacoordinate boron center. The dynamical stability of CBAl (1a) and CBAl (1b) was confirmed from the atom-centered density matrix propagation (ADMP) simulation over 20 ps of time at temperatures of 300 K and 400 K. The natural charge computations showed that the charges on the phB are almost zero in both systems. The 1a structure has σ/π-dual aromaticity as predicted from the nucleus independent chemical shift (NICS) values and the gauge-including magnetically induced ring current (GIMIC).
在此，我们首次报道了在中性团簇系统的全局最小能量结构中存在平面六配位硼（phB）原子。使用密度泛函理论（DFT）对CBAl系统的势能面（PES）进行了探索。CBAl（1a）和CBAl（1b）的全局最小值包含一个phB中心。然而，CBAl（1c）的全局最小值没有phB原子。分别应用CCSD(T)/aug-cc-pVTZ理论水平来计算相对于CBAl和CBAl系统的1a和1b结构的低位异构体的相对能量。对CB系统的PES探索表明，全局最小值不包含phB原子。然而，将铝（Al）原子引入CB部分会在CBAl系统中产生含有phB中心的结构。因此，Al金属在获得具有六配位硼中心的平面几何结构中起着重要作用。通过在300 K和400 K温度下超过20 ps时间的以原子为中心的密度矩阵传播（ADMP）模拟，证实了CBAl（1a）和CBAl（1b）的动力学稳定性。自然电荷计算表明，两个系统中phB上的电荷几乎为零。根据核独立化学位移（NICS）值和包含规范的磁诱导环电流（GIMIC）预测，1a结构具有σ/π-双重芳香性。
