A series of halido bis(silylamido) metalates of chromium to cobalt is reported. Reaction of [NBu4]Br with linear metal silylamides ML2 (M=Mn−Co, L=−N(SiMe3)2, −N(Dipp)SiMe3; Dipp=2,6‐iPr−C6H3) leads to NBu4[M(Br)L2] whereas for chromium either intramolecular deprotonation (L=−N(SiMe3)2) or ligand exchange (L=−N(Dipp)SiMe3) is observed. Attempts for their reduction with KC8 showed in part the formation of linear metal(I) silylamide complexes but also degradation. In contrast, analogous compounds bearing a [K{18c6}]+ counter ion of cobalt and iron, obtained from reaction of anionic linear metal(I) complexes [M{N(SiMe3)2}2]− with allyl bromide – can be cleanly reduced. The adduct formation studies are also extended to benzyl potassium yielding [KM(Bn)L2] (M=Mn, Co) and subsequently the salt separated [K{18c6}][M(Bn)L2] using 18‐crown‐6 as sequestrating agent.

The molecular compound [BiDipp2(SbF6)], containing the bulky, donor‐free bismuth cation [BiDipp2]+ has been synthesized and fully characterized (Dipp=2,6‐iPr2‐C6H3). Using its methyl analog [BiMe2(SbF6)] as a second reference point, the impact of steric bulk on bismuth‐based Lewis acidity was investigated in a combined experimental (Gutmann‐Beckett and modified Gutmann‐Beckett methods) and theoretical approach (DFT calculations). Reactivity studies of the bismuth cations towards [PF6]− and neutral Lewis bases such as isocyanides C≡NR’ revealed facile fluoride ion abstraction and straightforward Lewis pair formation, respectively. The first examples of compounds featuring bismuth‐bound isocyanides have been isolated and fully characterized.

Bi Lewis acidic: Donor‐free cationic bismuth compounds readily coordinate Lewis basic substrates including arenes, phosphanes, and isonitriles, and degrade the weakly coordinating counter‐anion [PF6]–. Counterintuitively, an increase in steric bulk around bismuth can increase the Lewis acidity. In the graphic, a bismuth kraken grabs Lewis basic substrates, solving scientific puzzles about bismuth‐based Lewis acidity. More information can be found in the Research Article by C. von Hänisch, C. Lichtenberg and co‐workers (DOI: 10.1002/chem.202204012).

Reactions between carbonyl diisocyanate or isothiocyanate and hydrogen halide gases as stereotypical nucleophiles show two different reaction pathways. The diisocyanate adds nucleophiles to form carbamoyl halides, whereas the isothiocyanate undergoes ring closure forming thiadiazines. These reactions indicate the significant influence of the chalcogen atom on the reaction products as well as their stability and characteristics. More information can be found in the Research Article by F. Tambornino and co‐workers (DOI: 10.1002/chem.202203983). Artwork by Janina Ill.

Invited for the cover of this issue are the groups of Carsten von Hänisch and Crispin Lichtenberg at the Philipps University of Marburg. The image depicts a bismuth kraken, eagerly grabbing Lewis basic substrates, thereby solving scientific puzzles about bismuth‐based Lewis acidity. Read the full text of the article at 10.1002/chem.202204012.