Synthesis and reactions of osmium(III) chloro carboxylates. X-ray crystal structure of tetra(µ-n-butyrato)-dichlorodiosmium(III)(Os–OS)

Abstract

The interaction of the hexachloroosmate(IV) ion, OsCl₆^2–, with acetic acid–acetic anhydride mixtures gives the compound Os₂(µ-O₂CMe)₄Cl₂. This brown insoluble paramagnetic compound on treatment with other carboxylic acids forms the exchanged compounds Os₂(µ-O₂CR)₄Cl₂(R = Et, Prⁿ, or CH₂Cl) that are more soluble in organic solvents. The binuclear bridged carboxylate structure has been established for the butyrate by X-ray diffraction. The crystals are monoclinic, space group P2₁/n, with a= 6.789(2), b= 11.790(1), c= 14.923(1)Å, β= 98.211(18)° and Z= 2. The Os–Os distance is 2.301(1)Å and Os–Cl is 2.417(3)Å. The interaction of Os₂(µ-O₂CMe)₄Cl₂ with various acids, sodium dimethyldithiocarbamate, aromatic amines, tertiary phosphines, and alkyl isocyanides has been studied.