High-frequency EPR study of the high-spin FeII complex Fe[(SPPh2)2N]2.

We report continuous-wave electron-paramagnetic-resonance (EPR) spectra of the high-spin Fe(II) complex Fe(SPPh(2))(2)N at 275.7 GHz, 94.1 GHz and 9.5 GHz. Combined analysis of these EPR spectra shows that the complex occurs in multiple conformations. For two main conformations the spin-Hamiltonian parameters, which reflect the electronic structure of the complex, are accurately determined: (1) D=9.17 cm(-1) (275 GHz), E/D=0.021 and (2) D=8.87 cm(-1) (266 GHz), E/D=0.052. The EPR spectra obtained at 275.7 GHz on single crystals of the complex are essential for the analysis and in addition they reveal that the two main conformations occur at two magnetically distinguishable sites.