Homodimetallic iron(II) hydrazones: Syntheses, spectroscopic, electrochemical, and theoretical investigations. X-ray crystal structure of both syn- and anti- rotamers of [η 5 -Cp)Fe(η 6 -C 6 H 5 )-NHN=C (Me)-(η 5 -C 5 H 4 ) Fe(η5-Cp)] + PF 6 -

Carolina Manzur, MAURICIO DANIEL FUENTEALBA CARRASCO, Lorena Millán, Francisco Gajardo, David Carrillo, Jose A. Mata, Sourisak Sinbandhit, Paul Hamon, Jean René Hamon, Samia Kahlal, Jean Yves Saillard

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19 Scopus citations

Abstract

Two homogeneous series of homodimetallic iron(II) hydrazone complexes of general formula [CpFe(η 6 -p- RC 6 H 4 )-NHN=CH-(η 5 -C 5 H 4 )FeCp] + PF 6 - (Cp = η 5 -C 5 H 5 ): R = H, [5] + PF 6 - ; Me, [6] + PF 6 - ; MeO, [7] + PF 6 - ; Cl, [8] + PF 6 - ; and [CpFe(η 6 -p-RC 6 H 4 )-NHN=CMe-(η 5 -C 5 H 4 )FeCp] + PF 6 - : R = H, [9] + PF 6 - ; Me, [10] + PF 6 - ; MeO, [11] + PF 6 - , have been prepared. These hydrazones were stereoselectively obtained as their trans isomers about the N=C double bond, by reaction of the corresponding organometallic hydrazines [CpFe(η6-p-RC 6 H 4 NHNH 2 )] + PF 6 - , R = H, [1] + PF 6 - ; Me, [2] + PF 6 - ; MeO, [3] + PF 6 - ; and Cl, [4] + PF 6 - , with formylferrocene, CpFe(η 5 -C 5 H 4 -CHO), and acetylferrocene, CpFe(η 5 -C 5 H 4 -CO-Me), respectively. All the new compounds were characterized by elemental analysis and IR, UV-Vis and 1 H NMR spectroscopies. For compound [9] + PF 6 - , the activation energy ΔG # for the hindered rotations of the mixed sandwich [CpFe(η 6 -C 6 H 5 -)] + (41.8 ± 0.9 and 41.2 ± 3.7 kJ mol- 1 ) and the ferrocenyl unit (40.0 ± 3.2 kJ mol- 1 ) about the -NH-N=CMe- hydrazone backbone have been determined by variable temperature 1 H NMR spectroscopic studies. The electrochemical behavior of the dinuclear hydrazones was explored by cyclic voltammetry, and features the role of the cationic [CpFe(η 6 -arene)] 1 moiety as an electron acceptor. The crystalline and molecular structure of [9] + PF 6 - was determined by single crystal X-ray crystallographic analysis. The structure shows the presence of both syn and anti rotamers in the asymmetric unit. The analysis of the electronic structure of [9] + through DFT calculations indicate a strong perturbation of the metal centers by the hydrazone bridge as well as some metal-metal interaction through the bridge.

Original languageEnglish
Pages (from-to)213-221
Number of pages9
JournalNew Journal of Chemistry
Volume26
Issue number2
DOIs
StatePublished - 1 Jan 2002

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