  A bismuth bond, a type of pnictogen bonding interaction, occurs in chemical
systems when there is evidence of a net attractive interaction between the
electrophilic region of a covalently or coordinately bonded bismuth atom and
the nucleophilic region in another, or the same, molecular entity. In this
review, we report on the signatory details of bismuth bonding in several
crystalline systems, along with other non-covalent interactions such as
hydrogen and halogen bonds, which are important driving forces in the rational
design of various types of materials. Illustrative crystal structures were
retrieved through careful inspection of the Inorganic Crystal Structure
Database (ICSD) and Cambridge Structural Database (CSD). Although thousands of
crystal structures containing bismuth have been deposited in these databases,
we selected only a number in which the covalently or coordinately bonded
bismuth atoms have clearly conceived positive regions on their electrostatic
surfaces. We show that these positive regions on bismuth electrostatically
attract various Lewis bases, including, for example, O, N, F, P, Cl, Br, I, S,
Se, Te, and Bi atoms, as well as those with regions of pi density in arene
moieties, present in the same or different molecular entities, resulting in the
formation of bismuth bonds. The characteristics of bismuth bonds were evaluated
using several current state of the art techniques, including geometric features
such as inter and intramolecular distances, which were also used to verify the
less than the sum of van der Waals radii concept, and the use of interaction
angles, which indicate the presence of directionality.
