ansa-Zirconocene bearing methyl substituents at all positions adjacent to the bridgehead [(-C(Ph)HC(Ph)H-)(η5-2,5-Me2C5H2)2ZrCl2] (4) was synthesized in good yields (82%) through the reductive dimerization of 1,4-dimethyl-6-phenylfulvene utilizing ZrCl2•DME generated in situ. The structure of 4 was subsequently confirmed using X-ray crystallography. 4 exhibited excellent catalytic performance with regard to 1-decene oligomerization, which was carried out with the intention of preparing lubricant base stocks. High activities (21 x 106 g/mol-Zr•h activity; TON = 150000; TOF = 42 s-1) were observed at temperatures as high as 120 °C and the oligomer distribution was appropriate for lubricant application. The simulated distillation (SIMDIS) data confirmed that a wide range of oligomers were formed, ranging from dimer (2-mer) to 20-mer. A minimal amount of the dimer and oligomers larger than the 10-mer was formed (13 and 25 wt%, respectively). Alternatively, a typical unbridged complex such as (η5-nBuC5H4)2ZrCl2 primarily produced dimers (54 wt%), whereas ansa-zirconocene (EBI)ZrCl2 primarily produced oligomers larger than 10-mer (62 wt%). The methyl substituents at the positions adjacent to bridgehead in 4 played a significant role in the catalytic performance.
