Lewis Superacidic Heavy Pnictaalkene Cations: Comparative Assessment of Carbodicarbene-Stibenium and Carbodicarbene-Bismuthenium Ions.

We report a comprehensive assessment of Lewis acidity for a series of carbone-stibenium and -bismuthenium ions using the Gutmann-Beckett (GB) method. These new antimony and bismuth cations have been synthesized by halide abstractions from (CDC)PnBr and [(CDC)PnBr][Br] (CDC = carbodicarbene; Pn = Sb or Bi; py = pyridyl). The reaction of (CDC)SbBr () with one or two equivalents of AgNTf (NTf = bis(trifluoromethanesulfonyl)imide) or AgSbF gives stibaalkene mono- and dications of the form [(CDC)SbBr][A] (; = 1,2; A = NTf or SbF).

Indirect Access to Carbene Adducts of Bismuth- and Antimony-Substituted Phosphaketene and Their Unusual Thermal Transformation to Dipnictines and [(NHC)OCP][OCP].

The synthesis and thermal redox chemistry of the first antimony (Sb)- and bismuth (Bi)-phosphaketene adducts are described. When diphenylpnictogen chloride [PhPnCl (Pn = Sb or Bi)] is reacted with sodium 2-phosphaethynolate [Na[OCP]·(dioxane)], tetraphenyldipnictogen (PhPn-PnPh) compounds are produced, and an insoluble precipitate forms from solution. In contrast, when the -heterocyclic carbene adduct (NHC)-PnPhCl is combined with [Na[OCP]·(dioxane)], Sb- and Bi-phosphaketene complexes are isolated.

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

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 ] (8) and [(CDC)BiBr (THF) ][SbF ] (11), dications [(CDC)Bi(Ph)][SbF ] (9) and [(CDC)BiBr(THF) ][NTf ] (12), and trication [(CDC) Bi][NTf ] (13) have been synthesized via sequential halide abstractions from (CDC)Bi(Ph)Cl (7) and (CDC)BiBr (10). Notably, the dications and trication exhibit C Bi double dative bonds and thus represent unprecedented bismaalkene cations.