Next Article in Journal
Alteration of Intestinal Flora Stimulates Pulmonary microRNAs to Interfere with Host Antiviral Immunity in Influenza
Next Article in Special Issue
Substitution Effect on the Charge Transfer Processes in Organo-Imido Lindqvist-Polyoxomolybdate
Previous Article in Journal
Comparison of Phenols Content and Antioxidant Activity of Fruits from Different Maturity Stages of Ribes stenocarpum Maxim
Previous Article in Special Issue
Thermochemical Measurements of Alkali Cation Association to Hexatantalate
Open AccessArticle

A Charge-Transfer Salt Based on Ferrocene/Ferrocenium Pairs and Keggin-Type Polyoxometalates

Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain
Centro de Física de Materiales CFM (CSIC–UPV/EHU), Paseo Manuel Lardizabal 5, 20018 Donostia-San Sebastián, Spain
Departamento de Física Aplicada II, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, P. O. Box 644, 48080 Bilbao, Spain
BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940 Leioa, Spain
Author to whom correspondence should be addressed.
Molecules 2018, 23(12), 3150;
Received: 13 November 2018 / Revised: 27 November 2018 / Accepted: 29 November 2018 / Published: 30 November 2018
(This article belongs to the Special Issue Polyoxometalates and Polyoxometalate-Based Systems)
A new hybrid inorganic-organometallic salt has been obtained from the reaction of the Keggin-type silicotungstate anion with ferrocene in a water/methanol mixture as a result of the partial oxidation of ferrocene molecules to ferrocenium cations. Single-crystal X-ray diffraction analysis reveals the presence of four ferrocenium (FeIII) cations and one ferrocene (FeII) molecule per plenary Keggin anion in the crystal structure of [FeIII (Cp)2]4[SiW12O40]·[FeII(Cp)2]·2CH3OH (1). Compound 1 thus constitutes the first example in the literature in which ferrocenium and ferrocene species coexist in the structure of a polyoxometalate-based salt. The two crystallographically independent ferrocenium species in the asymmetric unit of 1 exhibit different configurations: One displays an eclipsed conformation with ideal D5h symmetry, whereas the conformation in the other one is staggered D5d. The crystal packing of 1 can be best described as an organometallic sub-lattice of ferrocenium and ferrocene species linked by a network of π-π interactions that generates rectangular cavities of about 14 × 10 Å in which strings of Keggin anions and methanol molecules are hosted, further connected to each other via weak OPOM···CMeOH-OMeOH···OPOM type hydrogen bonds. The charge-transfer nature of the salt has been studied by solid-state diffuse reflectance UV-Vis spectroscopy and the presence of magnetically isolated FeIII/FeII centres has been confirmed by Mössbauer spectroscopy. A topological study carried out on all of the pristine ferrocenyl species deposited in the Cambridge Structural Database (CSD) has allowed two main conclusions to be drawn: (1) these species tend to adopt extreme conformations (either eclipsed or staggered) with less than a 15% of examples showing intermediate states and (2) the oxidation state of the iron centres can be unequivocally assigned on the basis of a close inspection of the Fe···Cp distances, which allows ferrocene neutral molecules and ferrocenium cations to be easily distinguished. View Full-Text
Keywords: polyoxometalates; ferrocene; single-crystal x-ray diffraction; mössbauer spectroscopy polyoxometalates; ferrocene; single-crystal x-ray diffraction; mössbauer spectroscopy
Show Figures

Graphical abstract

MDPI and ACS Style

Artetxe, B.; Iturrospe, A.; Vitoria, P.; Ruiz-Bilbao, E.; S. Garitaonandia, J.; Gutiérrez-Zorrilla, J.M. A Charge-Transfer Salt Based on Ferrocene/Ferrocenium Pairs and Keggin-Type Polyoxometalates. Molecules 2018, 23, 3150.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Search more from Scilit
Back to TopTop