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. 2022 Nov 3;27(21):7545.
doi: 10.3390/molecules27217545.

2-Imidazoline Nitroxide Derivatives of Cymantrene

Kseniya Maryunina  1 , Gleb Letyagin  1   2 , Galina Romanenko  1 , Artem Bogomyakov  1   2   3 , Vitaly Morozov  1 , Sergey Tumanov  1   2 , Sergey Veber  1   2 , Matvey Fedin  1   2 , Evgeniya Saverina  3 , Mikhail Syroeshkin  3 , Mikhail Egorov  3 , Victor Ovcharenko  1   3
Affiliations

2-Imidazoline Nitroxide Derivatives of Cymantrene

Kseniya Maryunina et al. Molecules. .

Abstract

The 2-imidazoline nitroxide derivatives of cymantrene-2-(η5-cyclopentadienyl)tricarbonylmanganese(I)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (NNMn) and 2-(η5-cyclopentadienyl)tricarbonylmanganese(I)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl (INMn) were synthesized. It was shown that NNMn and INMn exhibit a sufficiently high kinetic stability both in solids and in solutions under normal conditions. Their structural characteristics, magnetic properties and electrochemical behavior are close to Re(I) analogs. This opens the prospect of using paramagnetic cymantrenes as prototypes in the design of Re(I) half-sandwiched derivatives for theranostics, where therapy is combined with diagnostics by magnetic resonance imaging due to the contrast properties of nitroxide radicals.

Keywords: cymantrene; manganeseorganic; nitroxide; paramagnets.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 3
Scheme 3
Synthesis of NNMn and INMn.
Scheme 1
Scheme 1
Organometallic nitroxide-substituted derivatives.
Scheme 2
Scheme 2
Nitronyl nitroxide NNMn and imino nitroxide INMn.
Figure 1
Figure 1
Fragments of crystal structure and the shortest intermolecular distances (Å) in NNMn (a) and INMn (b). Color scheme: Mn—green, O—red, C—grey, and N—blue. The H atoms, the geminal CH3 groups and disordered O atoms of NO groups in positions with a weight of 0.2 for INMn are omitted for clarity.
Figure 2
Figure 2
Experimental dependences µeff(T) for the nitronyl nitroxide NNMn (a—blue squares; solid thick black line — fitted data based on optimized parameters, Table S4) and imino nitroxide INMn (b—red triangles). Insets: experimental EPR spectra for NNMn (a—blue curve) and INMn (b—red curve) recorded at room temperature in a degassed and diluted toluene solution; solid thin black curves—their modeling (Table S5).
Figure 3
Figure 3
Redox processes of the NNMn/INMn molecules and CV curves of oxidation and reduction in NNMn (blue line) and INMn (red line) 5.0 × 10−3 M solutions in MeCN (a GC disk electrode d = 1.7 mm, supporting electrolyte 0.1 M Bu4NBF4/MeCN, the scan rate 100 mV s−1, T = 298 K).
See this image and copyright information in PMC

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