Cationic Bismuth Amides: Accessibility, Structure, and Reactivity

Abstract

The synthetic access to cationic bismuth compounds based on simple, monodentate, synthetically useful amido ligands, [Bi(NR ) (L) ] , has been investigated (R=Me, iPr, Ph; L=neutral ligand). With [BPh ] as a counteranion, the formation of contact ion pairs and subsequent phenyl transfer from B to Bi is observed. An intermediate of this reaction, [Bi(NMe ) (HNMe )(BPh )] (1), could be isolated and fully characterized. The use of a fluorinated tetraarylborate as a counteranion leads to more stable cationic bismuth amides. The solvent-separated ion pairs [Bi (μ -NMe ) (NMe ) (thf) ] (4) and [Bi(NiPr ) (thf) ] (5) were fully characterized, with [B(3,5-C H (CF ) ) ] anions balancing the positive charge. The coordination chemistry, aggregation in solution, and spectroscopic features of these compounds were investigated. Compounds 4 and 5 show an increased reactivity towards diisopropylcarbodiimide compared to their neutral parent compounds. These reactions result in formation of the first cationic bismuth guanidinates. Characterization techniques include H, B, C, N, F, and P (VT)NMR and IR spectroscopy, single crystal X-ray diffraction analysis, and DFT calculations.

Double CH Activation of a Masked Cationic Bismuth Amide

“…[9] Following this protocol, Bi(NPh 2 ) 3 (1), [10] abismuth compound bearing diarylamide ligands,was treated with one equivalent of the Brønsted acid HOTf in THF (Tf = SO 2 CF 3 ). [9] Following this protocol, Bi(NPh 2 ) 3 (1), [10] abismuth compound bearing diarylamide ligands,was treated with one equivalent of the Brønsted acid HOTf in THF (Tf = SO 2 CF 3 ).…”

Intramolecular Metal⋅⋅⋅π‐Arene Interactions in Neutral and Cationic Main Group Compounds

“…However, from spectroscopic data we postulated that 7 b may be the product of the phenyl‐transfer reaction, Bi(N{ t Bu Ar ≠ }{SiPh 3 })(Ph)Cl (Scheme ). In addition, while examples of cationic bismuth species balanced by tetraphenylborate anions are known, aryl‐transfer reactivity is also well documented in the literature, and has even been used successfully to access triarylbismuth compounds …”

“…However,f rom spectroscopic data we postulated that 7b may be the product of the phenyltransfer reaction, Bi(N{ tBu Ar°}{SiPh 3 })(Ph)Cl (Scheme 2). In addition, while examples of cationic bismuth speciesb alanced by tetraphenylborate anionsare known, [10,29] aryl-transfer reactivity is also well documented in the literature, [8a, 30] and has even been used successfully to access triarylbismuth compounds. [31] The composition of 7b was confirmed as Bi(N{ tBu Ar°}{SiPh 3 })(Ph)Clb yi ndependent synthesis of an authentic sample, achieved from the reactiono fl ithium salt 2b with BiPhCl 2 (Scheme 2).…”

“…This methodology was extended to include simple dialkylamide ligands ‐NMe 2 and ‐N i Pr 2 (e.g. F ) . A prominent feature in the solid‐state structures of these compounds is the presence of stabilizing Bi⋅⋅⋅Cl or Bi⋅⋅⋅π‐arene interactions, which are dependent on both the steric bulk of the ligand system and the nature of the anion.…”

Doppelte CH‐Aktivierung eines maskierten Bismutamid‐Kations

“…Beispiele dafürsind die Bildung eines Bismut-gebundenen einzähnigen Oxy-Aryldianions (Schema 1b)s owie dessen Reaktivitäti ns elektiven Insertionsreaktionen mit CO 2 und NO oder oxidativen C-C-Kupplungsreaktionen. [6b,7] In diesen Tr ansformationen wurde maximal eine C-H-Bindung pro Bismutatom aktiviert.Wirz eigen hier, dass die gesteigerte Reaktivitätk ationischer Bismutverbindungen [8,9] in Kombination mit dem Abbau von Ringspannung eine beispiellose,B ismut-vermittelte,doppelte CH-Aktivierung von Diphenylamid, (NPh 2 ) À , induziert. Die aktivierten Positionen kçnnen selektiven Funktionalisierungsreaktionen unterzogen werden.Kürzlich haben wir die Protonolyse von Bismutamiden als effiziente Syntheseroute zu kationischen Bismutspezies des Ty ps [Bi(NR 2 ) 2 (L) n ] + etabliert.…”