Insertion of CO₂ and COS into Bi–C Bonds: Reactivity of a Bismuth NCN Pincer Complex of an Oxyaryl Dianionic Ligand, [2,6-(Me₂NCH₂)₂C₆H₃]Bi(C₆H₂^tBu₂O)

The reactivity of the unusual oxyaryl dianionic ligand, (C₆H₂^tBu₂-3,5-O-4)^2–, in the Bi³⁺ NCN pincer complex Ar′Bi­(C₆H₂^tBu₂-3,5-O-4), 1, [Ar′ = 2,6-(Me₂NCH₂)₂C₆H₃] has been explored with small molecule substrates and electrophiles. The first insertion reactions of CO₂ and COS into Bi–C bonds are observed with this oxyaryl dianionic ligand complex. These reactions generate new dianions that have quinoidal character similar to the oxyaryl dianionic ligand in 1. The oxyarylcarboxy and oxyarylthiocarboxy dianionic ligands were identified by X-ray crystallography in Ar′Bi­[O₂C­(C₆H₂^tBu₂-3-5-O-4)-κ²O,O′], 2, and Ar′Bi­[OSC­(C₆H₂^tBu₂-3-5-O-4)-κ²O,S], 3, respectively. Silyl halides and pseudohalides, R₃SiX (X = Cl, CN, N₃; R = Me, Ph), react with 1 by attaching X to bismuth and R₃Si to the oxyaryl oxygen to form Ar′Bi­(X)­(C₆H₂^tBu₂-3,5-OSiR₃-4) complexes, a formal addition across five bonds. These react with additional R₃SiX to generate Ar′BiX₂ complexes and R₃SiOC₆H₃^tBu₂-2,6. The reaction of 1 with I₂ forms Ar′BiI₂ and the coupled quinone, 3,3′,5,5′-tetra-tert-butyl-4,4′-diphenoquinone, by oxidative coupling.