Some unusual complexes of iron with 1,10-phenanthroline and 2,2'-bipyridyl

Abstract

The following hydroxy-bridged iron(III) complexes have been isolated for the first time : [phen₂ Fe(OH)₂Fe phen₂](SO₄)₂,7H₂O, [phen₂ Fe(OH)₂Fe phen₂]Br₄,2H₂O, [bipy₂ Fe(OH)₂Fe bipy₂](SO₄)₂,9H₂O. Attempts to prepare thiocyanate derivatives of these complexes resulted unexpectedly in the synthesis of the compounds Fe(SCN)₂ phen₂,H₂O and [FeSCN phen₂]ClO₄ which were investigated in the light of the well-known complexes of the type FeX₂ chelate₂. The compound [Fe phen₃][Fe(CN)₄ phen],5H₂O which, except for water, has the same stoicheiometry as Fe(CN)₄ phen₂, is also described for the first time. The claim by Madeja (Chemicke Zvesti, 1965, 19, 186) that the compound Fe(SCN)₂ bipy₂ exists both as a red trans form (μ_eff 3.0 B.M.) and a violet cis form (μ_eff 5.2 B.M.) is not justified according to this work. It seems that the red form may be a mixture of the paramagnetic bis- and the diamagnetic tris-compounds.