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Reactivity of TerN(SiMe3)BiCl2Synthesis of an Aminobismuthenium Cation and TerN(SiMe3)Bi(N3)2

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posted on 2018-08-02, 17:50 authored by Jonas Bresien, Christian Hering-Junghans, Axel Schulz, Max Thomas, Alexander Villinger
The reaction of TerN­(SiMe3)­BiCl2 (1) (Ter = 2,6-bis­(2,4,6-trimethylphenyl)­phenyl) with Lewis acids such as GaCl3 and Ag­[OTf] (OTf = OSO2CF3) was studied. While the reaction of 1 with GaCl3 led to decomposition into bismuth black, TerNH2·GaCl3, and [TerNH3]­[GaCl4], the reactions of 1 with 1 and 2 equiv of Ag­[OTf] resulted in methyl/triflate exchange reactions affording TerN­(SiMe2OTf)­Bi­(Me)Cl (2) and TerN­(SiMe2OTf)­Bi­(Me)­OTf (3). To circumvent the methyl/triflate exchange, the diiodide compound TerN­(SiMe3)­BiI2 (5) and the azide-substituted derivatives TerN­(SiMe3)­Bi­(Cl)­N3 (6) and TerN­(SiMe3)­Bi­(N3)2 (7) were prepared, although it was not possible to isolate pure 7 because of small impurities of 6. All of the bismuth compounds (17) were characterized by single-crystal X-ray diffraction and NMR, IR, and Raman spectroscopy. According to quantum-chemical calculations, 3 can be regarded as a donor-stabilized aminobismuthenium cation with OTf as the counterion. As expected for bismuth compounds with aromatic scaffolds, Bi···π-arene interactions were observed. The influence of the substitution at the bismuth atom on the strength of this intramolecular interaction with the terphenyl moiety was studied by experimental (crystal structures) and theoretical methods. A correlation between the Lewis acidity (NBO charge) and the Bi···π-arene distance could be established.