The synthesis and isolation of a phosphinine selenide was achieved for the first time by reacting red selenium with 2,6-bis(trimethylsilyl)phosphinine. The rather large coupling constant of 1 J P,Se = 883 Hz is in line with a PÀ Se bond of high s-character. The σ-electron donating Me 3 Sisubstituents significantly increase the energy of the phosphorus lone pair and hence its basicity, making the heterocycle considerably more basic and nucleophilic than the unsubstituted phosphinine C 5 H 5 P, as confirmed by the calculated gas phase basicities. NBO calculations further reveal that the lone pairs of the selenium atom are stabilized through donor-acceptor interactions with antibonding orbitals of the aromatic ring. The novel phosphinine selenide shows a distinct reactivity towards hexafluoro-2-butyne, Au(I) Cl as well as i PrOH. Our results pave the way for new perspectives in the chemistry of phosphorus in low coordination.

The yet unknown 2‐amino‐substituted λ3,σ2‐phosphinines are phosphorus‐containing aniline derivatives. Calculations show that the strong interaction of the π‐donating NR2 group with the aromatic system results in a high π‐density at the phosphorus atom. We could now synthesize 2‐N(CH3)2‐functionalized phosphinines, starting from a 3‐N(CH3)2‐substituted 2‐pyrone and (CH3)3Si‐C≡P. Their reaction with CuBr⋅S(CH3)2 affords CuI complexes with the first example of a neutral phosphinine acting as a rare bridging μ2‐P‐4e donor‐ligand between two CuI centers. Our experimental and theoretical investigations show that 2‐aminophosphinines are missing links in the series of known 2‐donor‐functionalized phosphinines.

Die bisher unbekannten 2‐Amino‐substituierten λ3,σ2‐Phosphinine sind phosphorhaltige Anilinderivate. Theoretische Studien zeigen, dass die starke Wechselwirkung der π‐donierenden NR2‐Gruppe mit dem aromatischen System zu einer erhöhten π‐Dichte am Phosphoratom führt. Ausgehend von einem 3‐N(CH3)2‐substituierten 2‐Pyron und (CH3)3SiC≡P wurden erstmalig 2‐N(CH3)2‐funktionalisierte Phosphinine synthetisiert. Deren Reaktionen mit CuBr⋅S(CH3)2 ergaben CuI‐Komplexverbindungen, in denen erstmalig ein neutrales Phosphinin als seltener μ2‐P‐4e‐Donor‐Ligand durch Verbrückung zweier CuI‐Zentren auftritt. Unsere experimentellen und theoretischen Untersuchungen zeigen, dass 2‐Aminophosphinine die Lücke in der Serie bekannter 2‐Donor‐funktionalisierter Phosphinine schließen.

The very low basicity and nucleophilicity of the phosphorus donor in phosphinines can be drastically increased by introducing strongly σ‐donating Me3Si substituents to the aromatic phosphorus heterocycle. The highest gas‐phase basicity was found for 2,3,5,6‐tetrakis(trimethylsilyl)phosphinine, which is even more basic in the gas phase than pyridine. This finding led to the first quantitative synthesis of a phosphinine selenide by treating red selenium with 2,6‐bis(trimethylsilyl)phosphinine. More information can be found in the Full Paper by T. Böttcher, C. Müller, et al. (DOI: 10.1002/chem.202102390).