LOW-VALENT LANTHANIDES IN ORGANIC-SYNTHESIS, LIGAND EFFECTS ON THE REACTIVITY OF SOME DIVALENT AND TRIVALENT SAMARIUM AND YTTERBIUM COMPLEXES

This account describes our recent studies on the reactions of diaryl ketones with low valent lanthanides, and on the hexamethylphosphoramide (HMPA)-coordinated LnI(2) (Ln = Sm, Yb) complexes. Emphases are put on clarification of the relation between structures and reactivities of the complexes, The following issues are mainly addressed. 1) Isolation and structural characterization of samarium and ytterbium ketyl completes, 2) Solvent (ligand) effects on the reactivity of the ketyl complexes. 3) Isolation and structural characterization of an ytterbium benzophnone dianion complex, 4) Protonation at the aromatic ring vs, at the carbonyl group of samarium and ytterbium diaryl ketone dianion species by phenols. 5) Isolation and structural characterization of three types of HMPA-coordinated LnI(2) (Ln = Sm, Yb) complexes and evaluation of the HMPA effects observed in SmI2/HMPA mediated reactions.