Synthesis and characterization ofpara- andmeta-substituted benzeneseleninato complexes of tin(II), silver(I) and iron(II)

Summary New complexes of tin(II), silver([) and iron(II) withpara- andmeta-substituted benzeneseleninic acids are reported and studied by chemical analyses, spectroscopic methods, conductivity and magnetic measurements. The complexes, of the type Sn(XC₆H₄SeO₂)₂, Ag(XC₆H₄SeO₂) and Fe(H₂O)₂(XC₆H₄SeO₂)₂, were obtained by reaction of SnCl₂, · 2 H₂O. AgNO₃ and Fe(NH₄)₂(SO₄)₂·6 H₂O with the sodium benzeneseleninates, XC₆H₄SeO₂Na (X = H.p-Cl,m-Cl,p-Br,m-Br orp-Me). The i.r. spectral data suggest that the silver and iron complexes contain RSeO₂^– ligands which act as bidentates in O,O-seleninato complexes. All the iron complexes have a distorted octahedralD_4h symmetry. The number of bands in the i.r. spectra of the tin derivatives indicates that there is no equivalence in the manner in which the two seleninato ligands are bonded. We could suggest that the tin atoms are intermolecularly O.O-bonded via one RSeO₂^– group, whereas the second ligand is coordinated to the metal via one oxygen atom forming polymeric -tetrahedral derivatives.