10.1002/chem.201803402
Chemistry - A European Journal
COMMUNICATION
deviation of the measured effective moment from the calculated
spin-only value may be attributed to the orbital contribution of
Fe2+ species, an observation quite often noted in lit.42
designing new catalytic concept avoiding expensive transition
metals.
A DFT calculation {at the level of B3LYP/Lanl2dz(Fe), 6-
31+g*(H,C,O)} was performed to understand further the
electronic spin structure of triply reduced catalytically active
species III. The reduced species III in the septet state reveals
four unpaired electrons at the octahedral iron(II) center along
with two unpaired electrons on PLY moieties (Figure 1b). The
natural population analysis on III indicates that 3d orbital
occupancy is 6.2. This computed 3d orbital population for iron is
typical of FeII. This is fully consistent with other experimental
studies (EPR and magnetism). It is found that the iron center
has a spin density of 4.05 and rest of the spin density (for two
unpaired electrons) is distributed over the PLY framework
revealing that the open shell phenalenyl based radicals are fully
delocalized over three phenalenyl units, a typical observation
noted in earlier phenalenyl based radicals.25-28
Acknowledgements
We thank CSIR, India (Grant No. (01(2779/14/EMR-II) for
financial support. SC and JA thank IISER Kolkata for a research
fellowship. AJ thanks DST, India for Inspire fellowship. BKS
acknowledges SERB, Govt. of India, for awarding NPDF
fellowship (File No. PDF/2016/000213). SKM thanks Dr Vishal
Rai, IISER Bhopal for mass spectroscopy.
Keywords: Iron catalyst, Base metal, C-H arylation, Phenalenyl
radical, Radical catalysis
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