A major thrust of research in modern main group chemistry is the use of multidentate ligands to perturb geometries at p-block elements such that they deviate substantially from valence shell electron-pair repulsion (VSEPR) model predictions. Such perturbations can engender new electronic structure and reactivity that is not available to classical systems. This chapter focuses upon the application of this methodology to bismuth, which, given its large radius and metallic nature, offers many opportunities for coordination chemistry. Bismuth compounds that are geometrically constrained exhibit distinct molecular structure, spectroscopic features, and reactivity compared to lighter pnictogens and other p-block elements. Notably, their structures show remarkable dynamism as a function of phase, coupled with substantial changes in type of bonding. The electronic structure of such compounds is very flexible, which allows for tuning of key properties like Lewis acidity over a broad range by simple substitution. But such flexibility also challenges the use of standard descriptors that are adequate for understanding the bonding situation in classical compounds. Emergent applications in catalysis and bond activation to yield unprecedented new systems are discussed. The chapter culminates by highlighting some of the open questions in the field and areas where future contributions would be particularly impactful.