Insertion of CO<sub>2</sub> and COS into Bi–C
Bonds: Reactivity of a Bismuth NCN Pincer Complex of an Oxyaryl Dianionic
Ligand, [2,6-(Me<sub>2</sub>NCH<sub>2</sub>)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>]Bi(C<sub>6</sub>H<sub>2</sub><sup><i>t</i></sup>Bu<sub>2</sub>O)
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Abstract
The reactivity of the unusual oxyaryl
dianionic ligand, (C<sub>6</sub>H<sub>2</sub><sup><i>t</i></sup>Bu<sub>2</sub>-3,5-O-4)<sup>2–</sup>, in the Bi<sup>3+</sup> NCN pincer complex Ar′Bi(C<sub>6</sub>H<sub>2</sub><sup><i>t</i></sup>Bu<sub>2</sub>-3,5-O-4), <b>1</b>, [Ar′ = 2,6-(Me<sub>2</sub>NCH<sub>2</sub>)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>] has been explored with small molecule
substrates and electrophiles. The first insertion reactions of CO<sub>2</sub> 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 <b>1</b>. The oxyarylcarboxy and oxyarylthiocarboxy dianionic ligands
were identified by X-ray crystallography in Ar′Bi[O<sub>2</sub>C(C<sub>6</sub>H<sub>2</sub><sup><i>t</i></sup>Bu<sub>2</sub>-3-5-O-4)-κ<sup>2</sup>O,O′], <b>2</b>, and Ar′Bi[OSC(C<sub>6</sub>H<sub>2</sub><sup><i>t</i></sup>Bu<sub>2</sub>-3-5-O-4)-κ<sup>2</sup>O,S], <b>3</b>, respectively. Silyl halides and pseudohalides,
R<sub>3</sub>SiX (X = Cl, CN, N<sub>3</sub>; R = Me, Ph), react with <b>1</b> by attaching X to bismuth and R<sub>3</sub>Si to the oxyaryl
oxygen to form Ar′Bi(X)(C<sub>6</sub>H<sub>2</sub><sup><i>t</i></sup>Bu<sub>2</sub>-3,5-OSiR<sub>3</sub>-4) complexes,
a formal addition across five bonds. These react with additional R<sub>3</sub>SiX to generate Ar′BiX<sub>2</sub> complexes and R<sub>3</sub>SiOC<sub>6</sub>H<sub>3</sub><sup><i>t</i></sup>Bu<sub>2</sub>-2,6. The reaction of <b>1</b> with I<sub>2</sub> forms Ar′BiI<sub>2</sub> and the coupled quinone, 3,3′,5,5′-tetra-<i>tert</i>-butyl-4,4′-diphenoquinone, by oxidative coupling
