Cationization of Bi(NPh 2 ) 3 has recently been reported to allow access to single-and double-CH activation reactions, followed by selective transformation of Bi−C into C−X functional groups (X = electrophile). Here we show that this approach can successfully be transferred to a range of bismuth amides with two aryl groups at the nitrogen, Bi(NR aryl 2 ) 3 . Exchange of one nitrogen-bound aryl group for an alkyl substituent gave the first example of a homoleptic bismuth amide with a mixed aryl/ alkyl substitution pattern at the nitrogen, Bi(NPhiPr) 3 . This compound is susceptible to selective N−N radical coupling in its neutral form and also undergoes selective CH activation when transformed into a cationic species. The second CH activation is blocked due to the absence of a second aryl moiety at nitrogen. The Lewis acidity of neutral bismuth amides is compared with that of cationic species "[Bi(aryl)(amide)(L) n ] + " and "[Bi(aryl) 2 (L) n ] + " based on the (modified) Gutmann−Beckett method (L = tetrahydrofuran or pyridine). The heteroaromatic character of [Bi(C 6 H 3 R) 2 NH(triflate)] compounds, which are iso-valence-electronic with anthracene, is investigated by theoretical methods. Analytical methods used in this work include nuclear magnetic resonance spectroscopy, single-crystal X-ray diffraction, mass spectrometry, and density functional theory calculations.
Aminotroponiminate (ATI) ligands are a versatile class of redox-active and potentially cooperative ligands with a rich coordination chemistry that have consequently found a wide range of applications in synthesis and catalysis. While backbone substitution of these ligands has been investigated in some detail, the impact of electron-withdrawing groups on the coordination chemistry and reactivity of ATIs has been little investigated. We report here Li, Na, and K salts of an ATI ligand with a nitro-substituent in the backbone. It is demonstrated that the NO 2 group actively contributes to the coordination chemistry of these complexes, effectively com-peting with the N,N-binding pocket as a coordination site. This results in an unprecedented E/Z isomerisation of an ATI imino group and culminates in the isolation of the first "naked" (i. e., without directional bonding to a metal atom) ATI anion. Reactions of sodium ATIs with silver(I) and tritylium salts gave the first N,N-coordinated silver ATI complexes and unprecedented backbone substitution reactions. Analytical techniques applied in this work include multinuclear (VT-) NMR spectroscopy, single-crystal X-ray diffraction analysis, and DFT calculations.
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