A trimetallic bismuth-based allyl cation

The chemistry of low-valent bismuth compounds has recently unlocked new concepts in catalysis as well as unique electronic structure fundamentals. In this work, we describe the synthesis and characterization of a highly-reduced bismuth salt featuring a cationic core based on three contiguous Bi(I) centers. The triatomic bismuth-based core holds an electronic situation that mimics the description of the archetypical carbonbased π-allyl cation. Structural, spectroscopic and theoretical analyses validate the unique π-delocalization between the bismuth’s highly diffused 6p-orbitals, resulting in a 1.5 bond order between the Bi atoms. This electronic situation places this complex as the heaviest and non-radioactive π-allyl cation of the periodic table. Furthermore, we demonstrate that the newly synthesized complex is able to act as a synthon for the transfer of a Bi(I) cation to forge other low-valent organobismuth complexes.