Computational study of the diamane molecule and its boron nitride analogue

Using density functional theory, this study explores the properties of C12H6 and B6N6H6 molecules, which are the minimal bilayer molecular structures formed by covalently bonded carbon or boron nitride rings. We determined the structural and energy characteristics of these molecules, calculating values of quantum chemical descriptors that characterize their reactivity. Additionally, we calculated the infrared and Raman spectra necessary for the identification of the molecules. Molecular dynamics and reaction coordinate studies were employed to investigate the thermal stability and decomposition mechanisms. Our results reveal that the diamond-like C12H6 molecule is stable under normal conditions, while its boron nitride analog, B6N6H6, remains stable only at cryogenic temperatures. The B6N6H6 molecule exhibited high hardness (almost twice higher compared to C12H6), typical for polar boron nitride molecules. The energy gap between the highest occupied and lowest unoccupied molecular orbitals (HOMO-LUMO) was found to be 1.86 and 4.04 eV for C12H6 and B6N6H6, respectively. The thermal decomposition mechanisms indicate that the C12H6 molecule has an energy barrier of 1.23 eV, while B6N6H6 has a lower energy barrier of 0.84 eV, leading to decomposition times of 16 years and 2.5 minutes at 300 K, respectively. This detailed analysis provides insights into the potential applications and stability of these novel molecular structures.