A novel ytterbium (II) complex 2 supporting by a bridged bisphenolate ligand H(2)L(OC4H7) (L = C(4)H(7)OCH(2)N(CH(2)-2-OC(6)H(2)-3,5-Bu(2)(t))(2)) with a tetrahydrofuran donor on side-arm was synthesized in high yield and characterized by elementary analysis, IR, (1)H-NMR, and (13)C-NMR. Ring-opening polymerization of 1,3-trimethylenecarbonate (TMC) was carried out using complex 2 and a known complex [Me(2)NCH(2)CH(2)N(CH(2)-2-O-3,5-C(6)H(2)(Bu(t))(2))(2)]Yb 1 as the initiators, respectively. It was found that both complexes 1 and 2 can alone initiate the ring-opening polymerization of TMC, and complex 1 showed higher activity than complex 2. The activity of both complexes 1 and 2 was found to be higher than that of monodentate phenoxo ytterbium (II) complex (2,6-Bu(2)(t)-C(6)H(3)O)(2)Yb(THF)(3). (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 2693-2698, 2011