Synthesis and magnetochemical. Spectroscopic, and structural studies of new tris(NN-dialkyldiselenocarbamato)iron(IV) tetrafluoroborate complexes

Abstract

Four new [Fe^IV(Se₂CNR₂)₃]⁺ Complexes [R = C₂H₅(1), R₂N = morpholino (2), R₂N = piperidino (3), and R = CH₂C₆H₅(4)] have been prepared as BF₄^– salts, characterized by routine analytical and spectroscopic methods, and studied by variable-temperature magnetochemistry (100–300 K) and Mossbauer (120 K), e.s.r. (10–77 K), and X-ray photoelectron (300 K) spectroscopies. In addition, the molecular structure of (4) has been determined by X-ray crystallography with a= 33.213(18), b= 12.920(13), c= 10.748(10)Å, β= 90.26(4)°, Z= 4 and shown to possess D₃ macrosymmetry with the FeSe₆ core having six selenium donor atoms at the apexes of a co-ordination polyhedron which is intermediate between the idealized trigonal prismatic and trigonal antiprismatic geometries. Overall, the present study indicates these tris-diselenocarbamate complexes to be low-spin iron(IV) species, similar to their tris-dithiocarbamate counterparts.