Synthesis, X-ray crystal structure and spectroscopic characterization of heterotrinuclear oxo-centered complex [Fe2NiO(CH3CH2COO)6(H2O)3]

New oxo-bridge, mixed metal complex, [Fe2NiO(CH3CH2COO)6(H2O)3]·0.5H2O has been synthesized from the direct reaction between metal nitrate and propanoic acid and characterized by elemental analysis, infrared and electronic spectroscopy and single-crystal X-ray crystallography. This complex have a typical μ3-oxo trinuclear structure: (a) three metal atoms are situated in the apexes of the equilateral triangle; (b) μ3-oxygen atom and six propanoate ligands fulfill the bridge functions; (c) the monodentate water ligands complete the octahedral geometry of the metal ions. It crystallized in the triclinic, space group type P  1¯. Two strong bands were observed in IR spectra at ∼1590 and ∼1420 (cm−1) stretching vibrations, the coordination mode of the carboxylate ligand can be assigned on the basis of the difference (Δν ⩽ 200 cm−1) of these two frequencies.