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

The interaction of the hexachloroosmate(IV) ion, OsCl62–, 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)A, β= 98.211(18)° and Z= 2. The Os–Os distance is 2.301(1)A and Os–Cl is 2.417(3)A. The interaction of Os2(µ-O2CMe)4Cl2 with various acids, sodium dimethyldithiocarbamate, aromatic amines, tertiary phosphines, and alkyl isocyanides has been studied.