Selective mono- and dimetallation of a group 3 sandwich complex

The scandium Cp/COT hybrid sandwich compound [(eta(5)-C5H5)Sc(eta(8)-C8H8)] is resistant to metallation via conventional alkyllithium and lithium amide bases. In this work, clean, selective, stoichiometric and high-yielding mono- and dimetallation is accomplished using tandem trans-metal-trapping (TMT) involving LiTMP and iBu(2)AlTMP with deprotonation occurring selectively at the Cp and Cp/COT rings respectively, providing the first examples of selective metallation of a sandwich complex featuring a group 3 element.