Mehrfachbindungen zwischen hauptgruppenelementen und übergangsmetallen. CIII. cis-Dimethylbis(2,2-dimethylpropyl)-oxoosmium(VI): Röntgenstrukturanalyse eines gemischtalkylierten Osmiumoxids

Mixed-alkyl osmium oxides of formula (R¹)₂(R²)₂OsO accessible along two different synthetic approaches, exhibit cis configuration owing to the stereochemistry of the precursor complexes. This geometry has now been shown for the crystalline state by means of an X-ray diffraction study of cis-dimethylbis(2,2-dimethylpropyl)oxoosmium(VI) (4): monoclinic space group P21 /n; a 565.9(2), b 2650.1(5), and c 962.1(5) pm; β 99.05(2)°; R = 0.027, R_w = 0.017. The title compound (4) is a mixed-alkyl derivative of tetraalkyloxoosmium(VI) complexes and displays a slightly-distorted square pyramidal structure. The oxo ligand is in the apical position (_d(OsO) 166.9(3) pm), while the cis-oriented alkyl groups are found in the basal positions (d(OsC) 208.3(4) to 212.6(3) pm).