Graphical Abstract: This paper reports on the synthesis of a new trinuclear homometalic mixed-valent iron carboxylate cluster with furan-2-carboxylic acid. The complex with the formula [Fe2IIIFeIIO(C4H3OCOO)6(H2O)3]∙0.5CH3CN•2.25H2O was characterized by X-ray analysis that revealed that the compound crystalizes in the triclinic centrosymmetric group P-1, with the following unit cell parameters: a = 10.2758(6)Å, b = 11.5991(9) Å, c = 19.7349(15) Å, α = 105.060(7)°, β = 94.216(6)°, γ = 101.662(6)°.