LAUSR

The synthesis and characterization of a preparation of the [Fe{(SePPh 2) 2 N} 2 ] complex (1 Td) is described. X-ray crystallography shows that this system contains a tetrahedral FeSe 4 coordination sphere. The structural features of 1 Td are compared with those of similar first row transition element complexes, including a recently reported preparation of [Fe{(SePPh 2) 2 N} 2 ] (1 SP) exhibiting a highly unusual square planar FeSe 4 coordination sphere. The electronic structure of 1 Td was elucidated by magnetometry, high-frequency EPR, and Mossbauer spectroscopic studies, which reveal zero-field splitting (ZFS) parameters typical of high spin S = 2 tetrahedral Fe II sites. Accurate ZFS parameters (D = +8.22 cm −1 , E/D = 0.104) were obtained by analysis of the EPR spectra and compared with those of the analogous [Fe{(SPPh 2) 2 N} 2 ] complex. The findings of this work call for a thorough structural and physicochemical characterization of the literature 1 SP system.