title: Experimental and theoretical Mössbauer study of an extended family of [Fe8(μ4-O)4(μ-4-R-px)12X4] clusters.
abstract: Six [Fe(8)(μ(4)-O)(4)(μ-4-R-pyrazolato)(12)X(4)] complexes containing an identical Fe(8)(μ(4)-O)(4) core have been structurally characterized and studied by Mössbauer spectroscopy. In each case, an inner μ(4)-O bridged Fe(III) cubane core is surrounded by four trigonal bipyramidal iron centers, the two distinct sites occurring in a 1:1 ratio. The Mössbauer spectrum of each of the clusters consists of two quadrupole doublets, which, with one exception (X = NCS, R = H), overlap to give three absorption lines. The systematic variation of X and R causes significant changes in the Mössbauer spectra. A comparison with values for the same clusters computed using density functional theory allows us to establish an unequivocal assignment of these peaks in terms of a nested model for the overlapping doublets. The changes in Mössbauer parameters (both experimental and computed) for the 1-electron reduced species [Fe(8)(μ(4)-O)(4)(μ-4-Cl-pyrazolato)(12)Cl(4)](-) are consistent with a redox event that is localized within the cubane core.
authors.affiliation: Department of Inorganic Chemistry, Kazan State Technological University, Kazan, Russia.
authors.forename: Ekaterina M
authors.initials: EM
authors.lastname: Zueva
authors.forename: W M C
authors.initials: WM
authors.lastname: Sameera
authors.forename: Dalice M
authors.initials: DM
authors.lastname: Piñero
authors.forename: Indranil
authors.initials: I
authors.lastname: Chakraborty
authors.forename: Eamonn
authors.initials: E
authors.lastname: Devlin
authors.forename: Peter
authors.initials: P
authors.lastname: Baran
authors.forename: Katarina
authors.initials: K
authors.lastname: Lebruskova
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Sanakis
authors.forename: John E
authors.initials: JE
authors.lastname: McGrady
authors.forename: Raphael G
authors.initials: RG
authors.lastname: Raptis
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry*; D008958:Models, Molecular; D011720:Pyrazoles / Q000737:chemistry*; D015204:Spectroscopy, Mossbauer / Q000379:methods
chemical_list: D005290:Ferric Compounds; D011720:Pyrazoles