Relationship between CO fluxionality of carbonyl clusters in solution and thermal motion in the solid state

Abstract

Using difference vibrational parameters obtained from solid state X-ray data for [Ph₄P]₂[Rh₆C(CO)₁₃] and evaluated along different internuclear directions,it has been possible to show for [Rh₆C(CO)₁₃]^2– that there is extensive vibrational motion of the carbonyl ligands around the Rh₄-equatorial plane (Rh 1, 3, 5, 6); this behaviour in the solid state is exactly in accord with the lowest energy CO migrational pathway found by previous n.m.r. studies in solution.