Effect of Inter-Porphyrin Distance on Spin-State in Diiron(III) µ-Hydroxo Bisporphyrins.
Chemistry
; 22(41): 14585-97, 2016 Oct 04.
Article
em En
| MEDLINE
| ID: mdl-27555240
ABSTRACT
The synthesis, structure, and properties of bischloro, µ-oxo, and a family of µ-hydroxo complexes (with BF4 (-) , SbF6 (-) , and PF6 (-) counteranions) of diethylpyrrole-bridged diiron(III) bisporphyrins are reported. Spectroscopic characterization has revealed that the iron centers of the bischloro and µ-oxo complexes are in the high-spin state (S=(5) /2 ). However, the two iron centers in the diiron(III) µ-hydroxo complexes are equivalent with high spin (S=(5) /2 ) in the solid state and an intermediate-spin state (S=(3) /2 ) in solution. The molecules have been compared with previously known diiron(III) µ-hydroxo complexes of ethane-bridged bisporphyrin, in which two different spin states of iron were stabilized under the influence of counteranions. The dimanganese(III) analogues were also synthesized and spectroscopically characterized. A comparison of the X-ray structural parameters between diethylpyrrole and ethane-bridged µ-hydroxo bisporphyrins suggest an increased separation, and hence, less interactions between the two heme units of the former. As a result, unlike the ethane-bridged µ-hydroxo complex, both iron centers become equivalent in the diethylpyrrole-bridged complex and their spin state remains unresponsive to the change in counteranion. The iron(III) centers of the diethylpyrrole-bridged diiron(III) µ-oxo bisporphyrin undergo very strong antiferromagnetic interactions (J=-137.7â
cm(-1) ), although the coupling constant is reduced to only a weak value in the µ-hydroxo complexes (J=-42.2, -44.1, and -42.4â
cm(-1) for the BF4 , SbF6 , and PF6 complexes, respectively).
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Chemistry
Assunto da revista:
QUIMICA
Ano de publicação:
2016
Tipo de documento:
Article
País de afiliação:
Índia