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

Red or orange crystals of [Co(NH3)6]2Cl2[Fe(CN)6] · 4H2O (1), [Co(en)3]2Cl2[Fe(CN)6] · 2H2O (2) and [Co(en)3]4[Fe(CN)6]3 · 21.6H2O (3) were isolated from the aqueous systems Co3+–LN–[Fe(CN)6]4− (LN = NH3, 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(CN) 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(NH3)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.

Graphical abstractThree new Co(III)–Fe(II) complexes based on hexacyanoferrates were prepared, characterized by IR, UV–Vis and Mössbauer spectroscopy, and their ionic crystal structures were elucidated by single crystal X-ray structure analysis. By combination of all methods the electronic states Co(III) LS and Fe(II) LS were determined.Figure optionsDownload full-size imageDownload as PowerPoint slide