TY  - JOUR
A1  - Hanft, Anna
A1  - Rottschäfer, Dennis
A1  - Wieprecht, Nele
A1  - Geist, Felix
A1  - Radacki, Krzysztof
A1  - Lichtenberg, Crispin
T1  - Aminotroponiminates: Impact of the NO\(_{2}\) Functional Group on Coordination, Isomerisation, and Backbone Substitution
JF  - Chemistry—A European Journal
N2  - 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 NO2 group actively contributes to the coordination chemistry of these complexes, effectively competing 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.
KW  - aminotroponiminates
KW  - non-coordinate anionic ligand
KW  - isomerisation
KW  - electrophilic substitution
KW  - alkali metal
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256988
VL  - 27
IS  - 57
ER  - 
TY  - JOUR
A1  - Hanft, Anna
A1  - Radacki, Krzysztof
A1  - Lichtenberg, Crispin
T1  - Cationic Bismuth Aminotroponiminates: Charge Controls Redox Properties
JF  - Chemistry – A European Journal
N2  - The behavior of the redox‐active aminotroponiminate (ATI) ligand in the coordination sphere of bismuth has been investigated in neutral and cationic compounds, [Bi(ATI)\(_{3}\)] and [Bi(ATI)\(_{2}\)L\(_{n}\)][A] (L=neutral ligand; n=0, 1; A=counteranion). Their coordination chemistry in solution and in the solid state has been analyzed through (variable‐temperature) NMR spectroscopy, line‐shape analysis, and single‐crystal X‐ray diffraction analyses, and their Lewis acidity has been evaluated by using the Gutmann–Beckett method (and modifications thereof). Cyclic voltammetry, in combination with DFT calculations, indicates that switching between ligand‐ and metal‐centered redox events is possible by altering the charge of the compounds from 0 in neutral species to +1 in cationic compounds. This adds important facets to the rich redox chemistry of ATIs and to the redox chemistry of bismuth compounds, which is, so far, largely unexplored.
KW  - aminotroponiminates
KW  - bismuth
KW  - cationic species
KW  - redox chemistry
KW  - redox-active ligands
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225669
VL  - 27
IS  - 20
SP  - 6230
EP  - 6239
ER  -