Three Co(III)–Fe(II) complexes based on hexacyanoferrates: Syntheses, spectroscopic and structural characterizations

Abstract

Red or orange crystals of [Co(NH 3) 6] 2Cl 2[Fe(CN) 6] · 4H 2O ( 1), [Co( en) 3] 2Cl 2[Fe(CN) 6] · 2H 2O ( 2) and [Co( en) 3] 4[Fe(CN) 6] 3 · 21.6H 2O ( 3) were isolated from the aqueous systems Co 3+–L N –[Fe(CN) 6] 4− (L N = NH 3, en = 1,2-diaminoethane). In all isolated samples the combination of Mössbauer ( δ values were from the range −0.07 to −0.08 mm/s) and IR spectra ( ν(C N) stretching vibrations in the range 2015–2047 cm −1) confirms the presence of low spin Fe(II) in [Fe(CN) 6] 4− anions. X-ray structure analyses corroborate the ionic character of all studied compounds. These contain diamagnetic [Co(NH 3) 6] 3+ ( 1) or [Co( en) 3] 3+ ( 2 and 3) complex cations and diamagnetic [Fe(CN) 6] 4− complex anions. In compounds 1 and 2 chloride anions are present, too. All three compounds contain water of crystallization, in compound 3 as many as 21.6 molecules per formula unit.