title: Structures of Fe(II) spin-crossover complexes from synchrotron powder-diffraction data.
abstract: Crystal structure determination and analysis have been carried out for the two spin-crossover compounds [Fe(teeX)(6)](BF(4))(2) (teeX is haloethyltetrazole; X = I: teei; X = Br: teeb), in both their high-spin (near 300 K) and their low-spin states (T = 90 K), using high-resolution powder-diffraction data collected at the ESRF (Grenoble, France) and SPring8 (Japan) synchrotron radiation facilities. The structures of teei have been solved using various direct-space structure determination techniques (grid search, genetic algorithm and parallel tempering) and refined with the Rietveld method using geometrical restraints. In the case of teeb, a structural model was found but a full refinement was not successful because of the presence of a significant amount of an amorphous component. Analysis of the structures (space group P2(1)/c, Z = 2) and diffraction data, and the absence of phase transitions, show the overall structural similarity of these compounds and lead to the conclusion that the gradual spin-crossovers are likely to be accompanied by small structural changes only.
authors.affiliation: University of Amsterdam, Faculty of Science, van 't Hoff Institute for Molecular Sciences, Laboratory for Crystallography, Nieuwe Achtergracht 166, NL-1018 WV Amsterdam, The Netherlands. eva@science.uva.nl
authors.forename: Eva
authors.initials: E
authors.lastname: Dova
authors.forename: René
authors.initials: R
authors.lastname: Peschar
authors.forename: Makoto
authors.initials: M
authors.lastname: Sakata
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kato
authors.forename: Arno F
authors.initials: AF
authors.lastname: Stassen
authors.forename: Henk
authors.initials: H
authors.lastname: Schenk
authors.forename: Jaap G
authors.initials: JG
authors.lastname: Haasnoot