DETERMINATION OF ELECTRON-PARAMAGNETIC-RESONANCE PARAMETERS FOR OSMIUM(III) LOW-SPIN SYSTEMS USING GRAPHICAL SOLUTIONS

Optical absorption and electron paramagnetic resonance (EPR) results f or the low-spin compounds [Os(NH3)(5)L][O3SCF3](n) [L = 4,4'-dithiodip yridine (dtdp) or H2O, n = 3; L = O3SCF3, n = 2] are reported. The EPR powder spectrum is analysed and from the three:experimental g values the crystal-held parameters and the energy levels are determined. The negative sign obtained for the axial splitting in [Os(NH3)(5)(dtdp)][O 3SCF3] has been interpreted to be the result of an Os-III --> L back-b onding interaction. The IR optical spectrum shows a broad band at 2080 nm that is compared to the estimate obtained from the EPR results. An alytical expressions for the crystal-field parameters and energy level s of the system are derived. In addition, an alternative graphical met hod which simplifies the estimation of ligand-field parameters from th e EPR parameters is presented.