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(C6H2tBu2O)

Abstract

The reactivity of the unusual oxyaryl dianionic ligand, (C6H2(t)Bu2-3,5-O-4)(2-), in the Bi(3+) NCN pincer complex Ar'Bi(C6H2(t)Bu2-3,5-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(t)Bu2-3-5-O-4)-κ(2)O,O'], 2, and Ar'Bi[OSC(C6H2(t)Bu2-3-5-O-4)-κ(2)O,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(t)Bu2-3,5-OSiR3-4) complexes, a formal addition across five bonds. These react with additional R3SiX to generate Ar'BiX2 complexes and R3SiOC6H3(t)Bu2-2,6. 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.