CONFORMATIONAL FLEXIBILITY IN C(2)X(4)-BRIDGED BIMETALLIC COMPLEXES

The full two-dimensional potential energy surface for the chair-to-cha ir rearrangement of (CP2Ti)2(mu-C2S4) is presented. This complex, in w hich one metal Lies above the plane of the ethylenetetrathiolate bridg e while the other Lies below the plane in a chairlike conformation, un dergoes an intramolecular rearrangement that is facile on the NMR time scale. The transition state for this process possesses a boat-shaped conformation, and the calculated activation energy agrees closely with those found in other related systems. The transition state results fr om maximizing of carbon-sulfur pi antibonding interactions in the boat form. Ln addition, the electronic effects which dictate the shapes in two analogous systems, (Cp(2)Ti)(2)(mu-C2O4) and (CP2Ti)(2)(mu-C-2(NH )(4)), are addressed.