Synthesis and reactivity of a six-membered heterocyclic 1,3-diphosphaallene.

1,3-Diphosphaallenes are a new class of heavier heteroallenes and show a fascinating chemical behavior and reactivity. Herein we report on the room temperature transformation of gallaphosphene LGa(OCP)PGaL 1 (L = HC[C(Me)N(Ar)], Ar = 2,6-i-PrCH) to the six-membered metallaheterocycle LGa(PCP)OGaL 2 featuring a LGa-substituted 1,3-diphosphaallene unit. The possible mechanism of formation of 2 is supported by quantum chemical calculations, which revealed that the formation of 2 is energetically more favorable ( 2 kcal mol) than the formation of 1 at ambient temperature.

In situ Cyclization of Aromatic Thioethers in Emissive Materials to Generate Phosphorescent Dibenzothiophenes.

In this contribution, we explored the photocyclization of thioethers to highly substituted dibenzothiophenes (DBT) using solely UV-light without any need for additives. This cost-effective, robust and environmentally friendly approach yielded phosphorescent compounds, which were characterized by X-ray crystallography and state-of-the-art photophysical methods. The resulting DBTs feature ultralong photoluminescence lifetimes and quantum yields close to unity in frozen glassy matrices.

Indium(III)-Catalyzed Haloalkynylation Reaction of Alkynes.

Green chemistry strives for sustainability at the molecular level and is gaining increasing relevance in the development of chemical reactions. The haloalkynylation reaction is a highly atom-economical C-C coupling reaction that was previously only achieved using transition metal catalysts. It enables the introduction of an alkyne unit and a halogen atom into the target molecule.

Catalytic hydroboration of aldehydes and ketones with an electron-rich acyclic metallasilylene.

The application of main group metal complexes in catalytic reactions is of increasing interest. Here we show that the electron-rich, acyclic metallasilylene L'(Cl)GaSiL C (L' = HC[C(Me)NDipp], Dipp = 2,6-PrCH; L = PhC(NBu)) acts as a precatalyst in the hydroboration of aldehydes with HBPin. Mechanistic studies with iso-valeraldehyde show that silylene C first reacts with the aldehyde with [2 + 1] cycloaddition in an oxidative addition to the oxasilirane 1, followed by formation of the alkoxysilylene LSiOCH[Ga(Cl)L']CHCHMe (2), whose formation formally results from a reductive elimination reaction at the Si center.

From Neutral Diarsenes to Diarsene Radical Ions and Diarsene Dications.

Diarsene [L(MeO)GaAs] (L=HC[C(Me)N(Ar)], Ar=2,6-PrCH, 4) reacts with MeOTf and NHC (NHC=1,3,4,5-tetra-methylimidazol-2-ylidene) to the diarsene [L(TfO)GaAs] (5) and the carbene-coordinated diarsene [L(MeO)GaAsAs(NHC)Ga(OMe)L] (6). The NHC-coordination results in an inversion of the redox properties of the diarsene 4, which shows only a reversible reduction event at E=-2.06 V vs Fc, whereas the carbene-coordinated diarsene 6 shows a reversible oxidation event at E=-1.