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FourC1-symmetricansa-metallocene complexes, C2H4(Ind)(2,7-tBu2-Flu)ZrCl2 (4), C2H4(3-Bn-Ind)(2,7-tBu2-Flu)ZrCl2 (5), C2H4(3-Bn-Ind)(3,6-tBu2-Flu)ZrCl2 (6), and C2H4(3-Bn-Ind)(2,7-tBu2-Flu)HfCl2 (7), were synthesized and characterized. The structures of complexes4,5, and7 were further determinedvia X-ray diffraction studies. Upon activation with modified methylaluminoxane (MMAO) or AliBu3/[Ph3C][B(C6F5)4] (TIBA/TrB), most of these complexes showed high efficiency in catalyzing propylene oligomerization/polymerization to afford products dominantly with allyl terminalsvia selectiveβ-methyl transfer (β-Me transfer). The introduction of 3-benzyl group on the indenyl ring of the complexes was found to be crucial in enabling highly selectiveβ-Me transfer during the polymerization process, leading to selectivities up to 89％ obtained by zirconocene complexes5 and6, and up to 91％ obtained by hafnocene complex7. Detailed chain-end analysis by1H-NMR,13C-NMR, and MALDI-TOF mass spectroscopy revealed that the allyl chain-ends of the polymeric products resulted from a selectiveβ-Me transfer process after two successively primary insertions of the monomer. Further studies concing the dependence of chain release selectivity as well as the molecular weight of products on monomer concentration suggested that bothβ-Me transfer (major) andβ-hydrogen transfer (β-H transfer) (minor) mediated by5/MMAO and 6/MMAO systems may mainly operate in a bimolecular pathway.