The chiral heterobimetallic complexes Li[Ln(eta(3):eta(1)-(C5R4SiMe2NCH2CH2R2)-Si-1)(2)] (Ln = Y,Lu; C5R41 = C5Me4, C5H4, 3-C(5)H(3)tBu; R-2 = OMe, NMe2; Me: methyl; tBu: tert-butyl) have been found to polymerize epsilon-caprolactone to give a polymer of high molecular weight ((M) over bar(n) > 20000) and moderate polydispersity ((M) over bar(W)/(M) over bar(n) < 2.0). Failure to observe a correlation between monomer/initiator ratio and molecular weight suggests a polymerization mechanism different from a pseudo-anionic mechanism.