Crystalline Divinyldiarsene Radical Cations and Dications

The divinyldiarsene radical cations [{(NHC)C(Ph)}As]2(GaCl4) (NHC=IPr: C{(NDipp)CH}2 3; SIPr: C{(NDipp)CH2}2 4; Dipp=2,6‐iPr2C6H3) and dications [{(NHC)C(Ph)}As]2(GaCl4)2 (NHC=IPr 5; SIPr 6) are readily accessible as crystalline solids on sequential one‐electron oxidation of the corresponding diviny...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2019-12, Vol.58 (49), p.17599-17603
Main Authors: Sharma, Mahendra K., Blomeyer, Sebastian, Neumann, Beate, Stammler, Hans‐Georg, Gastel, Maurice, Hinz, Alexander, Ghadwal, Rajendra S.
Format: Article
Language:English
Subjects:
Absorption spectroscopy
arsenic
Cations
Communication
Communications
Contraction
Crystal structure
Crystallinity
dications
Electrons
Elongation
Gallium chloride
Magnetic resonance spectroscopy
main-group compounds
NMR
NMR spectroscopy
Nuclear magnetic resonance
Oxidation
radicals
Spectrum analysis
π ligands
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Summary:The divinyldiarsene radical cations [{(NHC)C(Ph)}As]2(GaCl4) (NHC=IPr: C{(NDipp)CH}2 3; SIPr: C{(NDipp)CH2}2 4; Dipp=2,6‐iPr2C6H3) and dications [{(NHC)C(Ph)}As]2(GaCl4)2 (NHC=IPr 5; SIPr 6) are readily accessible as crystalline solids on sequential one‐electron oxidation of the corresponding divinyldiarsenes [{(NHC)C(Ph)}As]2 (NHC=IPr 1; SIPr 2) with GaCl3. Compounds 3–6 have been characterized by X‐ray diffraction, cyclic voltammetry, EPR/NMR spectroscopy, and UV/vis absorption spectroscopy as well as DFT calculations. The sequential removal of one electron from the HOMO, that is mainly the As−As π‐bond, of 1 and 2 leads to successive elongation of the As=As bond and contraction of the C−As bonds from 1/2→3/4→5/6. The UV/vis spectrum of 3 and 4 each exhibits a strong absorption in the visible region associated with SOMO‐related transitions. The EPR spectrum of 3 and 4 each shows a broadened septet owing to coupling of the unpaired electron with two 75As (I=3/2) nuclei. One‐by‐one electron oxidation of diarsenes [As2] featuring very efficient π‐donor N‐heterocyclic vinyl substituents with GaCl3 leads to the formation of radical cations [As2]+. and dications [As]2+ as crystalline solids. Experimental and computational studies revealed the delocalization of unpaired electron over the π‐conjugated CAs2C framework.
ISSN:1433-7851
1521-3773
1521-3773
DOI:10.1002/anie.201909144