Ethylene oligomerization method, and ethylene oligomer thereof

An ethylene oligomerization method comprising the step of producing an ethylene oligomer by reacting a chromium complex represented by chemical formula 1 and an organoaluminium compound represented by chemical formula 2 with ethylene at less than 60° C. in the presence of an organic solvent, wherein

• In chemical formula 1 and chemical formula 2,
• R is a C1-C60 alkyl or a C6-C60 aryl, a C2-C60 heteroaryl containing at least one heteroatom selected from the group consisting of O, N, S, SI, and P;
• R1 to R4 are independently a C1-C60 alkyl or a C6-C60 aryl, a C2-C60 heteroaryl containing at least one heteroatom selected from the group consisting of O, N, S, SI, and P;
• X1 and X2 are each independently a C1-C30 hydrocarbyl containing one or more selected from halogen, a C1-C30 alkyl, a C1-C30 alkylcarboxylate, acetylacetonate, or ether, and amino;
• A is boron or aluminum;
• Y1 to Y4 are independently a fluorine-substituted C6-C60 aryl, a fluorine-substituted C2-C60 heteroaryl containing at least one heteroatom selected from the group consisting of O, N, S, SI, and P, a fluorine-substituted C6-C60 aryloxy, or a fluorine-substituted C6-C60 alkoxy;
• R11 is a C4-C8 alkyl,
• wherein in R, R1 to R4, X1, X2, Y1 to Y4, and R11, the alkyl or aryl, heteroaryl may be further substituted with one or more selected from a C1-C30 alkyl, a C6-C30 aryl, a C1-C30 alkoxy, a monoC1-C30 alkylamino, a diC1-C30 alkylamino, a triC1-C30 alkylamino, a monoC6-C30 arylamino, a diC6-C30 arylamino, a triC6-C30 arylamino, a monoC1-C30 alkylsilyl, a diC1-C30 alkylsilyl, a triC1-C30 alkylsilyl, a monoC6-C30 arylsilyl, a diC6-C30 arylsilyl, and a triC6-C30 arylsilyl.