Insertion of CO and CS into Bi-N bonds enables catalyzed CH-activation and light-induced bismuthinidene transfer.

The uptake and release of small molecules continue to be challenging tasks of utmost importance in synthetic chemistry. The combination of such small molecule activation with subsequent transformations to generate unusual reactivity patterns opens up new prospects for this field of research. Here, we report the reaction of CO and CS with cationic bismuth(iii) amides.

Reactivity of a Cationic Bismuth Amide towards Unsymmetric Heterocumulenes.

Invited for this month's cover is the Lichtenberg group of the Philipps-University Marburg (Germany). The front cover picture shows "bismuth" dressed in colors reminiscent of those found on the surface of this element. In the graphic, bismuth is craving for soft ice cream.

Reactivity of a Cationic Bismuth Amide towards Unsymmetric Heterocumulenes.

The reactivity of a literature-known, ring-strained bismuth amide cation towards a range of unsymmetric heterocumulene substrates has been investigated. Reactions with ketenes R C=C=O (R=Me, Ph), isocyanates R'N=C=O, and isothiocyanates R'N=C=S (R'=Ph, 4-CF -C H ) proceed via facile insertion of the heterocumulene in the Bi-N bond of the cationic bismuth amide. Unexpectedly pronounced differences in the regioselectivity of these insertion reactions have been observed, yielding a rich variety of heterocycle motifs (BiC NC , BiC NCO, BiC NCS, BiC NCN), some of which are unprecedented.

Sulfinyl-aminotroponiminates: alkali- (Li, Na, K) and heavy-metal (Bi) complexes.

The installation of electron-withdrawing functional groups at the carbocyclic backbone of aminotroponiminate (ATI) ligands is a versatile method for influencing the electronic properties of the resulting ATI complexes. We report here Li, Na, and K salts of an ATI ligand with a phenylsulfinyl substituent in the backbone. It is demonstrated that the sulfinyl group actively contributes to the coordination chemistry of these complexes, effectively competing with neutral donor ligands such as thf or pyridine in the solid state (XRD), in solution (DOSY NMR spectroscopy), and in the gas phase (DFT).

CH Activation of Cationic Bismuth Amides: Heteroaromaticity, Derivatization, and Lewis Acidity.

Cationization of Bi(NPh) 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). 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(NPhPr).

The Dimethylbismuth Cation: Entry Into Dative Bi-Bi Bonding and Unconventional Methyl Exchange.

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, [BiMe (SbF )] (1), has been isolated and characterized.

Aminotroponiminates: Impact of the NO Functional Group on Coordination, Isomerisation, and Backbone Substitution.

Aminotroponiminate (ATI) ligands are a versatile class of redox-active and potentially cooperative ligands with a rich coordination chemistry that have consequently found a wide range of applications in synthesis and catalysis. While backbone substitution of these ligands has been investigated in some detail, the impact of electron-withdrawing groups on the coordination chemistry and reactivity of ATIs has been little investigated. We report here Li, Na, and K salts of an ATI ligand with a nitro-substituent in the backbone.

Cationic Bismuth Aminotroponiminates: Charge Controls Redox Properties.

The behavior of the redox-active aminotroponiminate (ATI) ligand in the coordination sphere of bismuth has been investigated in neutral and cationic compounds, [Bi(ATI) ] and [Bi(ATI) L ][A] (L=neutral ligand; n=0, 1; A=counteranion). Their coordination chemistry in solution and in the solid state has been analyzed through (variable-temperature) NMR spectroscopy, line-shape analysis, and single-crystal X-ray diffraction analyses, and their Lewis acidity has been evaluated by using the Gutmann-Beckett method (and modifications thereof). Cyclic voltammetry, in combination with DFT calculations, indicates that switching between ligand- and metal-centered redox events is possible by altering the charge of the compounds from 0 in neutral species to +1 in cationic compounds.

Bismuth Amides Mediate Facile and Highly Selective Pn-Pn Radical-Coupling Reactions (Pn=N, P, As).

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(NAr ) ] readily release aminyl radicals [NAr ] at ambient temperature in solution. These reactions yield the corresponding hydrazines, Ar N-NAr , as a result of highly selective N-N coupling.

Salicylaldimines: Formation via Ring Contraction and Synthesis of Mono- and Heterobimetallic Alkali Metal Heterocubanes.

The formation of salicylaldimine derivatives via ring contraction as byproducts in 2-aminotropone syntheses has been investigated. Salicylaldiminate (SAI) complexes of the alkali metals Li-K have been synthesized and transformed into heterobimetallic complexes. Important findings include an unusual double heterocubane structure of the homometallic sodium SAI, an unprecedented ligand-induced / isomerization of the aldimine functional group in the homometallic potassium SAI, and the first example of a structurally authenticated mixed-metal SAI based on s-block central atoms.

Alkali-Metal Aminotroponiminates: Selectivities and Equilibria in Reversible Radical Coupling of Delocalized π-Electron Systems.

Aminotroponiminates (ATIs) have recently been shown to belong to the growing class of redox-active ligands. The choice of the metal center allowed to switch between reversible electron transfer (M=Rh) and reductively induced dimerization (M=Na). Here, we investigate if the reductively induced dimerization of ATIs is a more general phenomenon for their alkali-metal complexes.

Aminotroponiminates: ligand-centred, reversible redox events under oxidative conditions in sodium and bismuth complexes.

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.