Carbodicarbene Bismaalkene Cations: Unravelling the Complexities of Carbene versus Carbone in Heavy Pnictogen Chemistry

Abstract

Abstract We report a combined experimental and theoretical study on the first examples of carbodicarbene (CDC)‐stabilized bismuth complexes, which feature low‐coordinate cationic bismuth centers with C=Bi multiple‐bond character. Monocations [(CDC)Bi(Ph)Cl][SbF 6 ] ( 8 ) and [(CDC)BiBr 2 (THF) 2 ][SbF 6 ] ( 11 ), dications [(CDC)Bi(Ph)][SbF 6 ] 2 ( 9 ) and [(CDC)BiBr(THF) 3 ][NTf 2 ] 2 ( 12 ), and trication [(CDC) 2 Bi][NTf 2 ] 3 ( 13 ) have been synthesized via sequential halide abstractions from (CDC)Bi(Ph)Cl 2 ( 7 ) and (CDC)BiBr 3 ( 10 ). Notably, the dications and trication exhibit C Bi double dative bonds and thus represent unprecedented bismaalkene cations. The synthesis of these species highlights a unique non‐reductive route to C−Bi π‐bonding character. The CDC‐[Bi] complexes ( 7 – 13 ) were compared with related NHC‐[Bi] complexes ( 1 , 3 – 6 ) and show substantially different structural properties. Indeed, the CDC ligand has a remarkable influence on the overall stability of the resulting low‐coordinate Bi complexes, suggesting that CDC is a superior ligand to NHC in heavy pnictogen chemistry.