title: Homoleptic 1-D iron selenolate complexes-synthesis, structure, magnetic and thermal behaviour of (1)(∞)[Fe(SeR)2] (R=Ph, Mes).
abstract: The first examples of polymeric homoleptic iron chalcogenolato complexes (1)(∞)[Fe(SePh)(2)] and (1)(∞)[Fe(SeMes)(2)] (Ph = phenyl = C(6)H(5), Mes = mesityl = C(6)H(2)-2,4,6-(CH(3))(3)) have been both prepared by reaction of [Fe(N(SiMe(3))(2))(2)] with two equivalents of HSeR (R = Ph, Mes) while (1)(∞)[Fe(SePh)(2)] was found to be also easily accessible through reactions of either FeCl(2), Fe(OOCCH(3))(2) or FeCl(3) with PhSeSiMe(3) in THF. In the crystal, the two compounds form one-dimensional chains with bridging selenolate ligands comprising distinctly different Fe-Se-Fe bridging angles, namely 71.15-72.57° in (1)(∞)[Fe(SePh)(2)] and 91.80° in (1)(∞)[Fe(SeMes)(2)]. Magnetic measurements supported by DFT calculations reveal that this geometrical change has a pronounced influence on the antiferromagnetic exchange interactions of the unpaired electrons along the chains in the two different compounds with a calculated magnetic exchange coupling constant of J = -137 cm(-1) in (1)(∞)[Fe(SePh)(2)] and J = -20 cm(-1) in (1)(∞)[Fe(SeMes)(2)]. In addition we were able to show that the ring molecule [Fe(SePh)(2)](12) which is a structural isomer of (1)(∞)[Fe(SePh)(2)] behaves magnetically similar to the latter one. Investigations by powder XRD reveal that the ring molecule is only a metastable intermediate which converts in THF completely to form (1)(∞)[Fe(SePh)(2)]. Thermal gravimetric analysis of (1)(∞)[Fe(SePh)(2)] under vacuum conditions shows that the compound is thermally labile and already starts to decompose above 30 °C in a two step process under cleavage of SePh(2) to finally form at 250 °C tetragonal PbO-type FeSe. The reaction of (1)(∞)[Fe(SePh)(2)] with the Lewis base 1,10-phenanthroline yielded, depending on the conditions, the octahedral monomeric complexes [Fe(SePh)(2)(1,10-phen)(2)] and [Fe(1,10-phen)(3)][Fe(SePh)(4)].
authors.affiliation: Institut für Nanotechnologie, Karlsruhe Institut für Technologie (KIT), Postfach 3640, Karlsruhe, 76021, Germany. andreas.eichhoefer@kit.edu
authors.forename: Andreas
authors.initials: A
authors.lastname: Eichhöfer
authors.forename: Gernot
authors.initials: G
authors.lastname: Buth
authors.forename: Francesco
authors.initials: F
authors.lastname: Dolci
authors.forename: Karin
authors.initials: K
authors.lastname: Fink
authors.forename: Richard A
authors.initials: RA
authors.lastname: Mole
authors.forename: Paul T
authors.initials: PT
authors.lastname: Wood
mesh_terms: D007501:Iron / Q000737:chemistry*; D008280:Magnetics; D008958:Models, Molecular; D008968:Molecular Conformation; D055620:Optical Phenomena; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D012643:Selenium / Q000737:chemistry*; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D009942:Organometallic Compounds; D007501:Iron; D012643:Selenium