Rare-earth bis(amides) {2-[Ph2Р(O)]C6H4NC(tBu)N(2,6-Me2C6H3)}Ln(N(SiMe3)2)2 (Ln = Y, Nd, La) coordinated by tridentate amidinate ligand were synthesized, structurally characterized and evaluated as catalysts for isoprene and rac-lactide polymerizations.