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Stepwise oxidations of a nickel(II)–iron(III) heterobimetallic porphyrin dimer: structure, spectroscopic and theoretical investigation

Published on Jan 1, 2019in Dalton Transactions4.05
· DOI :10.1039/C9DT01776C
Amit Kumar20
Estimated H-index: 20
(IITK: Indian Institute of Technology Kanpur),
Sayantani Banerjee1
Estimated H-index: 1
(IITK: Indian Institute of Technology Kanpur)
+ 1 AuthorsSankar Prasad Rath25
Estimated H-index: 25
(IITK: Indian Institute of Technology Kanpur)
Abstract
We have reported here the synthesis, structure and spectroscopic properties of the NiII–FeIII heterobimetallic ethene-bridged porphyrin dimer and investigate the effect upon step-wise one- and two-electron oxidations to produce a mixed-valence π–cation radical dimer and a dication diradical complex, respectively. We then investigate their electronic structure and spin coupling model and compare them with the corresponding homobimetallic analog. Detailed UV-vis-NIR, IR, and variable temperature magnetic studies and EPR and NMR spectroscopic investigations along with X-ray structure determination of the 2e-oxidized complex have demonstrated strong electronic communications through the bridge between two porphyrin π–cation radicals. The structure and geometrical parameters revealed the stabilization of the high-spin state of iron and the low-spin state of nickel in the 2e-oxidized complex. The extensive conjugation between the two porphyrin π–cation radicals has also altered the bridge from an ethylene to an exo-methylene moiety. Variable temperature magnetic studies of the 2e-oxidized complex revealed stronger antiferromagnetic coupling between two π–cation radical spins (Jr1–r2) of the NiII–FeIII heterodimer which is in sharp contrast to its diiron(III) analog where the porphyrin π–cation radical undergoes stronger antiferromagnetic coupling predominantly with the corresponding Fe(III) unpaired spin (JFe–r). The experimental observations are also strongly supported by DFT calculations.
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#1Firoz Shah Tuglak Khan (IITK: Indian Institute of Technology Kanpur)H-Index: 7
#2Amit Kumar (IITK: Indian Institute of Technology Kanpur)H-Index: 20
Last.Sankar Prasad Rath (IITK: Indian Institute of Technology Kanpur)H-Index: 25
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#1Firoz Shah Tuglak Khan (IITK: Indian Institute of Technology Kanpur)H-Index: 7
#2Syed Jehanger Shah (IITK: Indian Institute of Technology Kanpur)H-Index: 1
Last.Sankar Prasad Rath (IITK: Indian Institute of Technology Kanpur)H-Index: 25
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#1Amit Kumar (IITK: Indian Institute of Technology Kanpur)H-Index: 20
#2Debangsu Sil (IITK: Indian Institute of Technology Kanpur)H-Index: 12
Last.Sankar Prasad Rath (IITK: Indian Institute of Technology Kanpur)H-Index: 25
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#1Firoz Shah Tuglak Khan (IITK: Indian Institute of Technology Kanpur)H-Index: 7
#2Sayantani Banerjee (IITK: Indian Institute of Technology Kanpur)H-Index: 1
Last.Sankar Prasad Rath (IITK: Indian Institute of Technology Kanpur)H-Index: 25
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#1Firoz Shah Tuglak Khan (IITK: Indian Institute of Technology Kanpur)H-Index: 7
#2Anjani Kumar Pandey (IITK: Indian Institute of Technology Kanpur)H-Index: 2
Last.Sankar Prasad Rath (IITK: Indian Institute of Technology Kanpur)H-Index: 25
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#1Dipti Lai (IITK: Indian Institute of Technology Kanpur)H-Index: 2
#2Firoz Shah Tuglak Khan (IITK: Indian Institute of Technology Kanpur)H-Index: 7
Last.Sankar Prasad Rath (IITK: Indian Institute of Technology Kanpur)H-Index: 25
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#1Younis Ahmad Pandit (IITK: Indian Institute of Technology Kanpur)H-Index: 3
#2Sarnali Sanfui (IITK: Indian Institute of Technology Kanpur)H-Index: 1
Last.Sankar Prasad Rath (IITK: Indian Institute of Technology Kanpur)H-Index: 25
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