Abstract: | Crystal Structures and Vibrational Spectra of Tetrahalogenoacetylacetonatoosmates(IV), OsX4(acac)]?, X ? Cl, Br, I By reaction of the hexahalogenoosmates(IV) with acetylacetone the tetrahalogenoacetylacetonatoosmates(IV) OsX4(acac)]? (X = Cl, Br, I) are formed, which have been purified by chromatography and precipitated from aqueous solution as tetraphenylphosphonium (Ph4P) or cesium salts. X-ray structure determinations on single crystals have been performed of (Ph4P)OsCl4(acac)] ( 1 ) (triclinic, space group P1 , a = 9.9661(6), b = 11.208(2), c = 13.4943(7) Å, α = 101.130(9), β = 91.948(6), γ = 96.348(8)°, Z = 2), (Ph4P)OsBr4(acac)] ( 2 ) (monoclinic, space group P21/n, a = 9.0251(8), b = 12.423(2), c = 27.834(2) Å, β = 94.259(7)°, Z = 4) and (Ph4P)OsI4(acac)] ( 3 ) (monoclinic, space group P21/c, a = 18.294(3), b = 10.664(2), c = 18.333(3) Å, β = 117.68(2)°, Z = 4). Due to the increasing trans influence in the series O < Cl < Br < I the Os? O. distances of O.? Cl? X′ axes are lengthened and the OsO. stretching vibrations are shifted to lower frequencies. The Os? X′ bond lenghts are shorter as compared with symmetrically coordinated X? Os? X axes. |