title: Halide coordinated homoleptic [Fe4S4X4](2-) and heteroleptic [Fe4S4X2Y2](2-) clusters (X, Y = Cl, Br, I)--alternative preparations, structural analogies and spectroscopic properties in solution and solid state.
abstract: New facile methods to prepare iron sulphur halide clusters [Fe4S4X4](2-) from [Fe(CO)5] and elemental sulphur were elaborated. Reactions of ferrous precursors like tetrahalidoferrates(ii) or simple ferrous halides with [Fe(CO)5] and sulphur turned out to be efficient methods to prepare homoleptic [Fe4S4X4](2-) (X = Cl, Br) and heteroleptic clusters [Fe4S4X4-nYn](2-) (X = Cl, Br; Y = Br, I). Solid materials were obtained as salts of BTMA(+) (= benzyltrimethylammonium); the new compounds containing [Fe4S4Br4](2-) and [Fe4S4X2Y2](2-) (X, Y = Cl, Br, I) were all isostructural to (BTMA)2[Fe4S4I4] (monoclinic, Cc) as inferred from synchrotron X-ray powder diffraction. While the solid materials contain defined heteroleptic clusters with a halide X : Y ratio of 2 : 2, dissolving these compounds leads to rapid scrambling of the halide ligands forming mixtures of all five possible [Fe4S4X4-nYn](2-) clusters as could be shown by UHR-ESI MS. The variation of X and Y allowed assignment of the absorption bands in the visible and NIR; the long-wavelength bands around 1100 nm were tentatively assigned to intervalence charge transfer (IVCT) transitions.
authors.affiliation: Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln, Germany. axel.klein@uni-koeln.de and Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, INQUIMAE-CONICET, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, Piso 3, C1428EHA Buenos Aires, Argentina.
authors.forename: Andreas O
authors.initials: AO
authors.lastname: Schüren
authors.affiliation: Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln, Germany. axel.klein@uni-koeln.de.
authors.forename: Verena K
authors.initials: VK
authors.lastname: Gramm
authors.affiliation: Department Chemie und Pharmazie, Lehrstuhl für Bioanorgansiche Chemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Dürr
authors.affiliation: Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, INQUIMAE-CONICET, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, Piso 3, C1428EHA Buenos Aires, Argentina.
authors.forename: Ana
authors.initials: A
authors.lastname: Foi
authors.affiliation: Department Chemie und Pharmazie, Lehrstuhl für Bioanorgansiche Chemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany.
authors.forename: Ivana
authors.initials: I
authors.lastname: Ivanović-Burmazović
authors.affiliation: Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, INQUIMAE-CONICET, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, Piso 3, C1428EHA Buenos Aires, Argentina.
authors.forename: Fabio
authors.initials: F
authors.lastname: Doctorovich
authors.affiliation: Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln, Germany. axel.klein@uni-koeln.de.
authors.forename: Uwe
authors.initials: U
authors.lastname: Ruschewitz
authors.affiliation: Department für Chemie, Institut für Anorganische Chemie, Universität zu Köln, Greinstraße 6, 50939 Köln, Germany. axel.klein@uni-koeln.de.
authors.forename: Axel
authors.initials: A
authors.lastname: Klein