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          Institute: MPI für bioanorganische Chemie     Collection: MPI für bioanorganische Chemie     Display Documents

ID: 734270.0, MPI für bioanorganische Chemie / MPI für bioanorganische Chemie
Coordination of o-benzosemiquinonate, o-iminobenzosemiquinonate and aldimine anion radicals to oxidovanadium(IV)
Authors:Shit, Madhusudan; Bera, Sachinath; Maity, Suvendu; Weyhermüller, Thomas; Ghosh, Prasanta
Date of Publication (YYYY-MM-DD):2017
Title of Journal:New Journal of Chemistry
Journal Abbrev.:New J.Chem.
Issue / Number:11
Start Page:4564
End Page:4572
Review Status:Internal review
Audience:Experts Only
Abstract / Description:The study focuses on the stabilization of organic radicals by the oxidovanadium(IV) ion and it proves to be significant in exploring the bioactivity of vanadium. In addition to the o-benzosemiquinonate and o-iminobenzosemiquinonate anion radicals, the existence of reactive aldimine anion radicals coordinated to oxidovanadium(IV) ion was detected. Radical and non-radical oxidovanadium(IV) complexes of the types [(L-1)((VO)-O-IV)(acac)] (1), [(L-2)((VO)-O-IV)(acac)] (2), [(L-1)((VO)-O-IV)(sq(center dot))] (3), [(L-1)((VO)-O-IV)((t-Bu)sq(center dot))] (4), [(L-1)((VO)-O-IV)((NO2)isq(center dot-))] (5) and [(L-1(-))(2)((VO)-O-IV)(2)(SO4)]center dot 1/2CH(2)Cl(2) (6 center dot 1/2CH(2)Cl(2)) containing redox non-innocent tridentate NNO-donor aldimines (L1H and L2H) as coligands are reported (acac = acetylacetonato, sq(center dot-) = o-benzosemiquinonate, (t-Bu)sq(center dot-) = 3,5-di-tert-butyl-o-benzosemiquinonate and (NO2)isq(center dot-) = p-nitro-o-iminobenzosemiquinonate anion radicals). The sq(center dot-), (t-Bu)sq(center dot-) and (NO2)isq(center dot-) states in complexes were established by X-ray crystallography, EPR spectroscopy and solid state cross polarization magic angle spinning (CP/MAS) V-51 NMR spectroscopy, where the V-51 nuclei in 3-5 were deshielded in a range from -100.3 to +608.7 ppm. The cathodic waves of 1 and 2 due to L-1(-)/L-1(center dot 2-) and L-2(-)/L-2(center dot 2-) redox couples are reversible. Density functional theory (DFT) calculations authenticated that 1(-) and 2(-) are open shell pi radical (L-1(center dot 2-) and L-2(center dot 2-)) complexes of oxidovanadium(IV). The energies of the open shell singlet (OSS) and triplet solutions of 1(-) and 2(-) are lower than the corresponding closed shell singlet (CSS) solutions. In 1(-) and 2(-) ions, 35-39% beta spin is localized on the pi(star)(aldimine) function. The UV-vis-NIR absorption spectra of the complexes were analyzed by spectroelectrochemical measurements and time dependent (TD) DFT calculations.
Comment of the Author/Creator:Date: 2017, JUN 7 2017
External Publication Status:published
Document Type:Article
Version Comment:Automatic journal name synchronization
Communicated by:N. N.
Affiliations:MPI für bioanorganische Chemie
Identifiers:ISI:000402377400036 [ID No:1]
ISSN:1144-0546 [ID No:2]
DOI:10.1039/c7nj00186j [ID No:3]
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