The controlled release of well‐defined radical species under mild conditions for subsequent use in selective reactions is an important and challenging task in synthetic chemistry. We show here that simple bismuth amide species [Bi(NAr2)3] readily release aminyl radicals [NAr2]. at ambient temperature in solution. These reactions yield the corresponding hydrazines, Ar2N−NAr2, as a result of highly selective N−N coupling. The exploitation of facile homolytic Bi−Pn bond cleavage for Pn−Pn bond formation was extended to higher homologues of the pnictogens (Pn=N–As): homoleptic bismuth amides mediate the highly selective dehydrocoupling of HPnR2 to give R2Pn−PnR2. Analyses by NMR and EPR spectroscopy, single‐crystal X‐ray diffraction, and DFT calculations reveal low Bi−N homolytic bond‐dissociation energies, suggest radical coupling in the coordination sphere of bismuth, and reveal electronic and steric parameters as effective tools to control these reactions.

Cationization of Bi(NPh 2 ) 3 has recently been reported to allow access to single-and double-CH activation reactions, followed by selective transformation of Bi−C into C−X functional groups (X = electrophile). Here we show that this approach can successfully be transferred to a range of bismuth amides with two aryl groups at the nitrogen, Bi(NR aryl 2 ) 3 . Exchange of one nitrogen-bound aryl group for an alkyl substituent gave the first example of a homoleptic bismuth amide with a mixed aryl/ alkyl substitution pattern at the nitrogen, Bi(NPhiPr) 3 . This compound is susceptible to selective N−N radical coupling in its neutral form and also undergoes selective CH activation when transformed into a cationic species. The second CH activation is blocked due to the absence of a second aryl moiety at nitrogen. The Lewis acidity of neutral bismuth amides is compared with that of cationic species "[Bi(aryl)(amide)(L) n ] + " and "[Bi(aryl) 2 (L) n ] + " based on the (modified) Gutmann−Beckett method (L = tetrahydrofuran or pyridine). The heteroaromatic character of [Bi(C 6 H 3 R) 2 NH(triflate)] compounds, which are iso-valence-electronic with anthracene, is investigated by theoretical methods. Analytical methods used in this work include nuclear magnetic resonance spectroscopy, single-crystal X-ray diffraction, mass spectrometry, and density functional theory calculations.

The isolation of simple, fundamentally important, and highly reactive organometallic compounds remains among the most challenging tasks in synthetic chemistry. The detailed characterization of such compounds is key to the discovery of novel bonding scenarios and reactivity. The dimethylbismuth cation, [BiMe2(SbF6)] (1), has been isolated and characterized. Its reaction with BiMe3 gives access to an unprecedented dative bond, a Bi→Bi donor–acceptor interaction. The exchange of methyl groups (arguably the simplest hydrocarbon moiety) between different metal atoms is among the most principal types of reactions in organometallic chemistry. The reaction of 1 with BiMe3 enables an SE2(back)‐type methyl exchange, which is, for the first time, investigated in detail for isolable, (pseudo‐)homoleptic main‐group compounds.

Sodium complexes of aminotroponiminate (ATI) ligands have been reacted with a range of neutral donor ligands. Upon addition of crown ethers, they undergo an unusual ligandinduced disproportionation reaction with formation of [Na(A-TI) 2 ] À sodiate complex anions. The same structural motif has also been found in the first well-defined mixed-metal ATI complexes, which have been accessed starting from monometallic sodium and potassium species. The mixed-metal compounds confirm the possibility of ATIs to act as ditopic ligands. Using the polymerization of e-caprolactone as a model system, structure-reactivity-relationships in sodium and mixed-metal ATI compounds have been studied by comparing the reactivity of [Na(ATI)] and [Na(ATI) 2 ] À structural motifs. These studies revealed trends in the catalyst activity depending on the nuclearity of the complex and the substitution pattern at the ATI ligand. Exceptionally high activities were obtained for dinuclear sodium sodiates of type [Na(crown) 2 ][Na(ATI) 2 ], making them the most active alkali metal initiators for this reaction. The organometallic and polymeric compounds presented in this work have been characterized by techniques including (VT-)NMR spectroscopy, single-crystal X-ray diffraction, gel permeation chromatography, mass spectrometry, and DFT calculations.

A straightforward synthetic route to aminotroponate (AT) and aminotroponiminate (ATI) ligands with a ferrocenyl substituent at nitrogen is presented. Sodium derivatives have been synthesised and the first synthetic access to bismuth AT and ATI species has been demonstrated. All compounds show reversible ligand-centered redox events under oxidising conditions. In a homoleptic bismuth ATI complex, weak electronic communication between three ATI ligands was observed. The coordination chemistry and redox properties of AT and ATI compounds have been investigated by methods including NMR and UV/vis spectroscopy, single-crystal X-ray diffraction, cyclic voltammetry, and DFT calculations.