Crystal structures, vibrational spectra and normal coordinate analysis of fac-(Et4N)[OsF3Cl3] and fac-(Et4N) [IrF3Cl3]

By careful oxidation of the pure fluorochloroosmates(IV) or -iridates(IV) with BrF3 or KBrF4 in dichloromethane the mixed pentavalent complex anions fac-[OsF3Cl3](-) and fac-[IrF3Cl3](-) are formed. X-ray structure determinations on single crystals have been performed of cis-(Et4N)[OSF3Cl3] (1) (orthorhombic, space group Pbca, a = 11.225(5), b = 12.020(5), c = 21.873(5) Angstrom, Z = 8) and fac-(Et4N)[IrF3Cl3] (2) (orthorhombic, space group Pbca, a = 11.269(10) b = 12.049(1), c = 21.801(3) Angstrom, Z = 8), Based on the molecular parameters of the X-ray determinations the IR and Raman spectra for the anion of 1 and 2 have been assigned by normal coordinate analysis, The Osmium compound exhibits slightly higher valence force constants as compared with the Iridium complex: f(d)(OsF) = 3.25, f(d)(IrF) = 3.25, f(d)(OsCl) = 2.35 and f(d)(IrCl) = 2.25 mdyn/Angstrom.