Jahn-Teller effect in trigonal μ-oxoclusters

A theory of the Jahn-Teller effect in trinuclear Cr-III and Fe-III mu-oxocomplexes based oil the generalized angular overlap model is developed. The central bridging 0 atom is not localized at the center of the triangle formed by the metal atoms. Rather, it executes a free or hindered motion along a circular groove of radius 0.05-0.1 angstrom. The theory provides a qualitative explanation for apparent discrepancy between the X-ray structural data and the results of the heat capacity, magnetic susceptibility, and inelastic neutron scattering measurements. Namely, X-ray structural data correspond to a regular triangle symmetry while other data correspond to an equilateral or even irregular triangle symmetry.