Structural phase diagram and bonding patterns of BxHy (x + y = 20) binary systems: A theoretical investigation

Abstract

The borane clusters exhibit diverse geometries related with their special multi-center bonding patterns in different B/H ratios, due to the electronic deficiency character of boron atom. In this paper, global minimal structures of BxHy (x + y = 20) are predicted using unbiased structural search programs and their structural phase diagram is plotted. Relative energies of these clusters go down firstly and then rise up with B10H10 as the turning point, and B12H8, B16H4, B20 are magic numbers. The geometries of these clusters undergo the transition of 3D open cage − 3D closed cage – irregular 3D − 2D planar/quasi-planar along with the increasing B/H ratios, and their stability depends on flexibility of the multi-center bonding patterns. This study reveals the geometric evolution rule related with the electronic shells of BH binary systems, which makes sense in borane chemistry.