A new N-6 hexadentate ligand and a novel heptacoordinated N6O-type Fe(III) compounds: Synthesis, characterization and structure of [Fe(dimpyen)(OH)](A)(2) (A = PF6- or ClO4-)

作者：Ortega Villar Norma; Ugalde Saldivar Victor M; Flores Perez Blas; Flores Alamo Marcos; Real J A; Moreno Esparza Rafael^*

来源：Inorganica Chimica Acta, 2011, 375(1): 213-219.

DOI：10.1016/j.ica.2011.05.008

• Iron (III) complexes
• Hexadentate ligand
• Heptacoordination
• Redox properties
• Magnetic properties
• Crystal structure

In this contribution, we report the syntheses of a novel N-6 donor set ligand, dimpyen = N1,N2-di[(1-methyl-1H-2-imidazolyl) methyl]-N1, N2-di(2-pyridilmethyl)-1,2-ethanediamine. This type of ligand was designed to modulate the properties of the metal ions bound to it. The reaction with Fe(II) gives off a new heptacoordinated iron(III) complex. We study the spectroscopic (UV-Vis), magnetic and electrochemical behavior and also made the structural determination with X-ray diffraction at 134 K and a heptacoordinated N6O-type derivative of Fe(III) is reported as well. This complex crystallize as perchlorate or hexafluorophosphate and the formula of these derivatives are [Fe(dimpyen)(OH)](PF6)(2) (1) and [Fe(dimpyen)(OH)](ClO4)(2) (2) which both crystallize with an intermediate geometry, between pentagonal bipyramidal and monocapped octahedral. The UV-Vis spectra in CH3CN solution show a shoulder at 306 nm assigned to one ligand-metal charge-transfer (LMCT) transition, in addition, a weaker and wide band assigned to the charge transfer HO-Fe transition (lambda(max) at 404 nm with an extinction coefficient of 818 cm (1) M (1)) is also observed. The magnetic studies corroborate a high-spin iron (III) species in all the temperature range considered. Measurements of cyclic voltammetric confirm a reversible system Fe(III) species, with E-1/2 = -0.380 V/Fc(+)-Fc, this low potential value explains the high stability of the Fe(III) and the easy oxidation of Fe(II) by atmospheric O-2(g) reaction.

• 出版日期2011-9-1