Jump to main content
Jump to site search

Issue 48, 2016
Previous Article Next Article

Arylamino radical complexes of ruthenium and osmium: dual radical counter in a molecule

Author affiliations


Radical and non-radical ruthenium and osmium complexes of 1-amino-9,10-anthraquinone (AqNH2), which is defined as a molecule of dual radical counter, are disclosed. 1-Amido-9,10-anthraquinone (AqNH) complexes of the types trans-[RuII(AqNH)(PPh3)2(CO)Cl] (1), trans-[OsII(AqNH)(PPh3)2(CO)Br] (2) and trans-[RuIII(AqNH)(PPh3)2Cl2] (3) were isolated. AqNH of 1–3 is redox active and undergoes oxidation reversibly at +(0.05–0.35) V to the 1-amino-9,10-anthraquinone radical (AqNH˙) and reduction at -(0.86–1.60) V to the 1-amido-9,10-anthrasemiquinonate anion radical (AqNHSQ˙2−). The reaction of 2 with I2 in CH2Cl2 afforded a crystalline AqNH˙ complex of the type trans-[OsII(AqNH˙)(PPh3)2(CO)Br]+I5·½I2 (2+I5·½I2). AqNH˙ and AqNHSQ˙2− complexes of the types trans-[RuII(AqNH˙)(PPh3)2(CO)Cl]+ (1+), trans-[RuIII(AqNH˙)(PPh3)2Cl2]+ (3+), trans-[RuII(AqNHSQ˙2−)(PPh3)2(CO)Cl] (1) and trans-[OsII(AqNHSQ˙2−)(PPh3)2(CO)Br] (2) were generated chemically/electrochemically in solution. The electronic states of the complexes were authenticated by single crystal X-ray structure determinations of 1, 2·5/4 toluene, 3 and 2+I5·½I2, EPR spectroscopy and density functional theory (DFT) calculations. AqNH˙ instigates a 2c–3e pπ–dπ interaction and the Image ID:c6dt03728c-t1.gif length in 2+I5·½I2, 1.978(5) Å, is relatively shorter than the OsII–NHAq length, 2.037(2) Å, while the Aq–NH˙ bond, 1.365(8) Å, is longer than the Aq–NH bond, 1.328(3) Å. DFT calculations predicted that the atomic spin is delocalized over the ligand backbone (1+, 56%) particularly in one of the p-orbitals of the nitrogen and the metal atoms of the 1+ and 2+ ions, while the spin is dominantly localized on the anthraquinone fragment of the 1 and 2 ions. TD DFT calculations were employed to elucidate the origins of the lower energy absorption bands of the neutral complexes. Hypsochromic shifts of the UV-vis-NIR absorption maximum during 11+, 22+ and 33+ conversions were recorded by spectroelectrochemical measurements.

Graphical abstract: Arylamino radical complexes of ruthenium and osmium: dual radical counter in a molecule

Back to tab navigation

Supplementary files

Publication details

The article was received on 26 Sep 2016, accepted on 04 Nov 2016 and first published on 07 Nov 2016

Article type: Paper
DOI: 10.1039/C6DT03728C
Citation: Dalton Trans., 2016,45, 19428-19440
  •   Request permissions

    Arylamino radical complexes of ruthenium and osmium: dual radical counter in a molecule

    S. Bera, S. Maity, T. Weyhermüller and P. Ghosh, Dalton Trans., 2016, 45, 19428
    DOI: 10.1039/C6DT03728C

Search articles by author