Darstellung und Schwingungsspektren von Chloro-Bromo-Ruthenaten(IV) einschließlich der Stereoisomeren / Preparation and Vibrational Spectra of Chloro-Bromo-Ruthenates(IV) Including Stereoisomers

Abstract

<jats:title>Abstract</jats:title><jats:p> The mixed chloro-bromo complexes [RuCl<jats:sub>n</jats:sub>Br<jats:sub>6-n</jats:sub>]<jats:sup>2-</jats:sup>, n = 1-5, have been separated for the first time by ion exchange chromatography on diethylaminoethylcellulose. Due to the stronger trans-effect of Br compared with Cl, on treatment of [RuBr<jats:sub>6</jats:sub>]<jats:sup>2-</jats:sup> with Cl<jats:sup>-</jats:sup> in the presence of Br<jats:sub>2</jats:sub> nearly pure cis/fac-isomers,and by reaction of [RuCl<jats:sub>6</jats:sub>]<jats:sup>2-</jats:sup> withBr<jats:sup>-</jats:sup>/Br<jats:sub>2</jats:sub> nearly purer tranS/mer-isomersforn = 2,3,4 are formed. The vibrational spectra of the mixed ligand complexes are completely assigned according to point groups D<jats:sub>4h</jats:sub>, C<jats:sub>4v</jats:sub>, C<jats:sub>3v</jats:sub> and C<jats:sub>2v</jats:sub>, respectively. The bands are observed in the characteristic regions: ν(RuCl): 340-270 &gt; ν(RuBr): 245-190 &gt; δ(ClRuCl) ≥ δ(ClRubr) ≥ δ(BrRuBr): 125-90 &gt; νʟ: &lt; 100 cm<jats:sup>-1</jats:sup>. The lower stability of the hexahalogeno complexes of Ru(IV), 4d, compared with the homologous complexes of Os(IV), 5d, is confirmed by a decrease of the force field constants by approximately 15%.</jats:p>