Bismuth Polycations Revisited: Alternative Synthesis and Electronic Structure of Bi6Br7, and Bonding in Main-Group Polyatomic Ions from a Direct Space Perspective

Abstract

A bismuth subbromide, Bi6Br7, was synthesized in the form of single crystals using the reaction between Bi and Hg2Br2 in a gradient furnace. Its crystal structure was reinvestigated by low-temperature single-crystal X-ray diffraction (Pnnm, a = 15.4996(6) Å, b = 23.6435(7) Å, c = 9.0231(2) Å, Z = 8, R1 = 0.041, wRall = 0.087). Based on the diffraction data, the structure description was revised as containing Bi95+ cluster polycations and 1∞[Bi3Br145−] ladder-like anions. DFT calculations of band structure showed the compound to be a narrow-gap semiconductor with a band gap of ca. 1.3 eV, with the nature of the compound as ionic salt confirmed by charge density analysis. Direct-space bonding analysis based on the ELF topology and QTAIM partitioning, performed for all known homoatomic bismuth polycations, as well as isoelectronic main-group metal ions, shows patterns of localized pairwise and three-center bonding forming the frameworks of the clusters. In addition to obtaining new data, the use of highly augmented basis sets allowed us to revise and amend several previously made conclusions regarding bonding in such species.

Ternary aromatic and anti-aromatic clusters derived from the hypho species [Sn2Sb5]3−

“…Thus, it is the formation of the multicenter 3c–2e and 5c–2e bonding elements that provides extra stabilization of the complex. In addition to AdNDP, the topology analysis of the electron localization function 48 (ELF) was performed for this cluster, as additional valuable method for determination of chemical bonding of Zintl clusters 49 . The ELF results are fully consistent with the AdNDP picture (Supplementary Fig.…”

Bismuth Infrared Star: Being at a Glance

“…Bi 6 stoichiometry also presents two possible clusters: Bi 6 2+ with antiprism structure of C 3v symmetry and Bi 6 4+ with octahedral (O h ) structure. It's important to clarify that Bi 6 2+ was identified in the crystalline phase on the example of Bi 6 [PtBi 6 Cl 12 ] phase, [56] while the Bi 6 4+ cluster was studied only theoretically [23] . Nevertheless, we decided to investigate both.…”

“…It's important to clarify that Bi 6 2 + was identified in the crystalline phase on the example of Bi 6 [PtBi 6 Cl 12 ] phase, [56] while the Bi 6 4 + cluster was studied only theoretically. [23] Nevertheless, we decided to investigate both. Each polycation possesses six 1c-2e lone pairs with ON = 1.99e.…”

“…Moreover, in order to rationalize the structural features of the clusters, earlier bonding analysis was performed using an investigation of the canonical MO, [21] ELF topology, [22] and QTAIM partitioning. [23] In the current work, we extend this area and apply the Adaptive Natural Density Partitioning (AdNDP) method for bismuth clusters. This method is capable of providing not only Lewis's bonding elements (1c-2e lone pairs and 2c-2e "classical" bonds) but also a non-classic multi-center representation of delocalized bonds (nc-2e bonds, where n � 3), which allows to introduce the concepts of aromaticity naturally.…”

“…[21] that bismuth clusters obey modified Wade's rules, created for boron Hydrides. Moreover, in order to rationalize the structural features of the clusters, earlier bonding analysis was performed using an investigation of the canonical MO, [21] ELF topology, [22] and QTAIM partitioning [23] . In the current work, we extend this area and apply the Adaptive Natural Density Partitioning (AdNDP) method for bismuth clusters.…”