Six tetranuclear complexes [Fe (III) 3 Ln (μ3 -O) 2 (CCl3 COO) 8 (H2 O) (THF) 3] THF C7 H16 [Ln=Gd (III) (1), Tb(III) (2), Dy(III) (3), Ho(III) (4), Y(III) (5), and Lu(III) (6)] have been studied by magnetic susceptibility and Mössbauer spectroscopy. These isostructural molecules have a "butterfly" structure core consisting of two Fe2 Ln (μ3 -O) triangular "wings" which share a common Ln-Fe "body"; the dihedral angle between the wings is ca. 148°. The coordination spheres of the iron ions are essentially distorted octahedral. The lanthanides are eight-coordinate with coordination polyhedra that may be described as distorted tetragonal bipyramids. Variable-temperature solid-state magnetic susceptibility in the temperature range 1.8-300 K and magnetization at 1.8 K for compounds 1-6 were measured. The spin state of Fe is S=5/2 in all cases. In compounds 5 and 6, where Ln(III) (Y and Lu, respectively) is diamagnetic, the three Fe atoms form an obtuse isosceles triangle with antiferromagnetic interactions JFe-Fe =-50K between the wing-tip Few and body Feb atoms, and negligible interaction between the Few 's, resulting in a ground state of effective spin S=5/2 per cluster. In the complexes with paramagnetic lanthanide ions, the interaction between the Fe3 triangle and the Ln(III) center is described by an effective exchange constant which is antiferromagnetic and 1 order of magnitude weaker. Besides, at 3 K incipient spin blocking, characteristic of single molecule magnets, was found to occur in the out-of-phase component of the ac susceptibility in , and { Fe3 HoO2 }. The activation energy of a Debye process describing the magnetization reversal has been determined to be, Ea 8, 9, and 10 K for the Ln=Tb, Dy, and Ho, respectively, and the prefactor τ0 10-7 s. The high spin states of the Fe(III) centers were confirmed by the Mössbauer spectra, in which two distinguishable Fe sites could be resolved above 80 K, corresponding to the Few and Feb sites, respectively. Relatively larger values of the quadrupole splitting of the Mössbauer spectra were observed for the Few pair as compared with that for the Feb, and both quadrupole splittings diminished with increasing temperature. At 3 K the Mössbauer spectra showed a state with blocked spins (sextets) for the { Fe3 TbO2 } and { Fe3 DyO2 } cases. From the Ea and τ0, determined in the ac susceptibility, the relaxation time at 3 K is estimated as τ 10-5 - 10-6 s much longer than the time window of Mössbauer spectroscopy and compatible with the single molecule magnet behavior. In the presence of a strong magnetic field the moments of the Ln(III) cation and the Fe3 triangle are polarized. For some compounds at low temperature a magnetic pattern (sextet) for each of the three Fe sites appeared, and the antiferromagnetic coupling within the Fe3 cluster was directly proved by the opposite trend of the field dependence of the two Few sextets as compared with the Feb third one.