Stepwise oxidations of a nickel(ii)-iron(iii) heterobimetallic porphyrin dimer: structure, spectroscopic and theoretical investigation.
Dalton Trans
; 48(27): 10089-10103, 2019 Jul 21.
Article
en En
| MEDLINE
| ID: mdl-31179478
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.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Dalton Trans
Asunto de la revista:
QUIMICA
Año:
2019
Tipo del documento:
Article
País de afiliación:
India
Pais de publicación:
Reino Unido