For producing high molecular weight copolymers of ethylene and I-hexene, a series of silicon-bridged fluorenyl-phenoxy group 4 complexes R2Si(Flu)(3-'Bu-5-Me-2-C6H2O)MCl2 (4a: M = Ti; R = Me; Flu = fluoren-9-yl; 4b: M = Ti; R = Et; Flu = fluoren-9-yl; 4c: M = Ti; R Me; Flu = 2,7-'Bu-2-fluoren-9-yl; 4d: M = Ti; R = Et; Flu = 2,7-'Bu-2-fluoren-9-yl; 8: M = Zr; R Me; Flu 2,7-'Bu-2-fluoren-9-yl; 9: M = Hf; R = Me; Flu = 2,7-'Bu-2-fluoren-9-yl) were prepared by two methods. One was a reaction of MCl4 (M = Ti, Zr, and Ho with the dilithium salts generated by treating corresponding ligands 1a-d with "BuLi in the presence of Et3N in toluene and the other used MCl2(NR'(2))(2) (6a: M = Ti; R' = Me, 6b: M = Zr; R' = Et, 6c: M = Hf, R' = Me) instead of MCl4 followed by successive chlorination with Me3SiCl. X-ray crystallographic study of 4d indicated that the cyclopentadienyl moiety of the fluorenyl ligand is bound to the titanium atom in a fashion between eta(3) and eta(5). The newly prepared titanium Complexes 4a-d exhibited high catalytic activities for copolymerization of ethylene and 1-hexene in the presence of 'Bu3Al/[Me3NHPh][B(C6F5)(4)] and afforded higher molecular weight copolymers than the parent tetramethyl-substituted cyclopentadienyl titanium complex Me2Si(eta(5)-C5Me4)(3-'Bu-5-Me-2-C6H2O)TiCl2 (10). In particular, the active species generated from complex 4d was thermally stable and exhibited high polymerization activities even at 210 degrees C and produced high molecular weight copolymers with good 1-hexene content.