Cationic Bismuth Amides: Accessibility, Structure, and Reactivity

The synthetic access to cationic bismuth compounds based on simple, monodentate, synthetically useful amido ligands, [Bi(NR 2 ) 2 (L) n ] + , has been investigated (R=Me, i Pr, Ph; L=neutral ligand). With [BPh 4 ] − 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 2 ) 2 (HNMe 2 )(BPh 4 )] ( 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 2 (μ 2 ‐NMe 2 ) 2 (NMe 2 ) 2 (thf) 6 ] 2+ ( 4 ) and [Bi(N i Pr 2 ) 2 (thf) 3 ] + ( 5 ) were fully characterized, with [B(3,5‐C 6 H 3 (CF 3 ) 2 ) 4 ] − 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 1 H, 11 B, 13 C, 15 N, 19 F, and 31 P (VT)NMR and IR spectroscopy, single crystal X‐ray diffraction analysis, and DFT calculations.