Abstract: An ?-olefin oligomer having the following features (1) to (6), and a method for producing the ?-olefin oligomer using a particular double-crosslinked meso complex provide an ?-olefin oligomer that contains a smaller amount of a dimer component while having a low viscosity, not in accordance with the Schulz-Flory distribution, and a method for producing the same: (1) a trimer component proportion C3 (% by mass) that is larger than a theoretical value obtained from the S—F distribution, (2) a hexamer component proportion C6 (% by mass) that is smaller than a theoretical value obtained from the S—F distribution, (3) a kinematic viscosity at 100° C. of 20 mm2/s or less, (4) a meso triad fraction [mm] measured by 13C-NMR of 40% by mol of less, (5) from 0.2 to 1.

Abstract: An ?-olefin polymer has (A) a tacticity index(meso triad fraction)[mm] of 10 to 50 mol %, (B) a kinematic viscosity at 100° C. of 200 to 10,000 mm2/s, (C) a content of a dimer and a trimer is less than 2 mass %, and (D) an average number of carbon atoms of 4 to 30.

Abstract: A method for producing an unsaturated dimer by reacting an ?-olefin having 6 to 14 carbon atoms in an agitated vessel, wherein a metallocene-based catalyst is used as a reaction catalyst; and the supply flow rate of hydrogen (VH) to the vessel is 0.2 to 1.2 [(NL/hr) per L of olefin] and the agitation power (Pv) is 0.18 KW/m3 or more of the time of reaction.

Abstract: A method of producing an ?-olefin oligomer composition of the present invention is a method of producing an ?-olefin oligomer composition, the method including the step of causing the molecules of an ?-olefin to react with each other with a specific catalyst in the presence of hydrogen.