The oxo-centred trinuclear complex [Fe3O(O2CPh)(6)(py)(3)]ClO4. py and its fully deuteriated analogue have been synthesized. X-Ray crystallography at T=233 K shows that the complex has threefold symmetry, space group P6(3)/m. Incoherent inelastic neutron scattering spectra at T=1.5 K however show the presence of two inequivalent sets of molecules, one a static "isosceles" coupled system, with two J values for the three metal-metal interactions, the other a dynamic system, with rapid pseudorotation between equivalent isosceles geometries. Combining infrared and neutron scattering data, the distortion of the cluster has been estimated.