Photoelectron Spectroscopy of Size-Selected Bismuth-Boron Clusters: BiBn- (n=6-8)

Because of its low toxicity, bismuth is considered to be a green metal and has received increasing attention in chemistry and materials science. To understand the chemical bonding of bismuth, here we report a joint experimental and theoretical study on a series of bismuth-doped boron clusters, BiBn- (n = 6-8). Well-resolved photoelectron spectra are obtained and are used to understand the structures and bonding of BiBn- in conjunction with theoretical calculations. Global minimum searches find that all three BiBn- clusters have planar structures with the Bi atom bonded to the edge of the planar Bn moiety via two Bi-B sigma bonds as well as pi bonding by the 6p(z) orbital. BiB6- is found to consist of a double-chain B-6 with a terminal Bi atom. Both BiB7- and BiB8- are composed of a Bi atom bonded to the planar global minima of the B-7(-) and B-8(-) clusters. Chemical bonding analyses reveal that BiB6- is doubly antiaromatic, whereas BiB7- and BiB8- are doubly aromatic. In the neutral BiBn (n = 6-8) clusters, except BiB6 which has a planar structure similar to the anion, the global minima of both BiB7 and BiB8 are found to be half-sandwich-type structures due to the high stability of the doubly aromatic B-7(3-) and B-8(2-) molecular wheel ligands.

Automated summary

A joint experimental and theoretical study on a series of bismuth-doped boron clusters was conducted to understand the structures and bonding of BiBn-. The clusters were found to have planar structures with specific bonding characteristics, exhibiting different aromaticity properties.