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Aminotroponiminates: Impact of the NO 2 Functional Group on Coordination, Isomerisation, and Backbone Substitution
Author(s) -
Hanft Anna,
Rottschäfer Dennis,
Wieprecht Nele,
Geist Felix,
Radacki Krzysztof,
Lichtenberg Crispin
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202102324
Subject(s) - isomerization , substituent , chemistry , coordination complex , reactivity (psychology) , ligand (biochemistry) , substitution reaction , crystallography , stereochemistry , crystal structure , metal , medicinal chemistry , catalysis , organic chemistry , medicine , biochemistry , alternative medicine , receptor , pathology
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 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.