The [Fe{(SePPh2)2N}2] Complex Revisited: X‐ray Crystallography, Magnetometry, High‐Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral FeIISe4 Coordination Sphere

The synthesis and characterization of complex [Fe{(SePPh 2 ) 2 N} 2 ] ( 1 ) is described. X‐ray crystallography shows that this system contains a tetrahedral FeSe 4 coordination sphere. The structural features of 1 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 was elucidated by magnetometry, high‐frequency EPR, and Mössbauer 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.